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At least 19 recordsLinked to original sources
USGS2012

Western pond turtle: Biology, sampling techniques, inventory and monitoring, conservation, and management: Northwest Fauna No. 7

One of only two native, freshwater turtle species in the western United States, western pond turtles are declining in portions of their original range. Declines are mostly due to habitat loss, introduction of non-native species, pollution, and lack of connectivity among populations. USGS zoologist R. Bruce Bury and colleagues from the U.S. Forest Service, California State University, and other agencies compiled and edited a new review and field manual of this charismatic species. Objectives were to determine its current distribution and abundance, summarize and evaluate population features, review techniques to detect population and habitat changes, and improve monitoring for long-term trends. Methods described in the manual should improve consistency, efficiency, and accuracy of survey data, resulting in improved management and conservation efforts.

Book↗
USGS1997

Late quaternary regional geoarchaeology of Southeast Alaska Karst: A progress report

Karst systems, sea caves, and rock shelters within the coastal temperate rain forest of Alaska's Alexander Archipelago preserve important records of regional archaeology, sea level history, glacial and climatic history, and vertebrate paleontology. Two 14C AMS dates on human bone discovered in a remote cave (49-PET-408) on Prince of Wales Island document the oldest reliably dated human in Alaska to ca. 9800 B.P. A series of 14C AMS dates from cave deposits span the past 40,000 years and provide the first evidence of Pleistocene faunas from the northwest coast of North America. Other discoveries include sea caves and marine beach deposits elevated above modern sea level, extensive solution caves, and mammalian remains of species previously undocumented within the region. Records of human activity, including cave art, artifacts, and habitation sites may provide new insights into the early human colonization of the Americas. ??1997 John Wiley & Sons, Inc.

Alaska↗
USGS1984

Neogene molluscan stages of the West Coast of North America

Neogene marine sediments of the West Coast of North America were deposited in a series of widely spaced basins that extended geographically from the western and northern Gulf of Alaska (60°N) to southern California (33°N). Rich molluscan faunas occur extensively throughout these deposits and form the basis for biostratigraphic schemes that are useful for correlating within and between individual basins. Early biostratigraphic work was concerned with faunas from particular horizons and with the stratigraphic range of diverse taxa, such as Pecten and Turritella , without reference to other fossil groups. Succeeding work increasingly dealt with the relationships of molluscan zones to benthic and, later, planktonic foraminiferal stages. In recent years the age limits of Neogene molluscan stages have become better documented by reference to planktonic microfossils from dated DSDP cores and onshore faunas. Neogene molluscan faunas from California, the Pacific Northwest states (Oregon and Washington), and southern Alaska have been treated separately due to differences in faunal composition and geographic isolation. As a result, a different biostratigraphic sequence has been described for each region. Pacific Northwest stages have been formally named and defined, and their names are also used informally for Alaskan faunas. California Neogene stages were proposed early in this century, are in need of redescription, and their usage is informal. Precise correlations between the three regional sequences have not yet been achieved, due to the low number of co-occurring species and the general lack of planktonic microfossils in these largely shallow-water faunas. The objectives of ongoing research include: fuller documentation of the faunas of California and Pacific Northwest stages; formal description of California stages; improved correlation between regional stage sequences; refinement of age estimates for stage boundaries; and, establishment of Neogene stages for Alaskan faunas.

California, Oregon, Washington↗
USGS1984

An overview of paleogene molluscan biostratigraphy and paleoecology of the Gulf of Alaska region

Paleogene marine strata in the Gulf of Alaska region occur in three geographic areas and may be characterized by their molluscan faunal composition and paleoecology: a western area consisting of the Alaska Peninsula, Kodiak Island, and adjacent islands; a central area encompassing Prince William Sound; and an eastern area extending from the mouth of the Copper River to Icy Point in the Lituya district. Strata in the western area include the Ghost Rocks, Narrow Cape (in part), Sitkalidak, Stepovak, Belkofski, and Tolstoi Formations; in the central area Paleogene strata are assigned entirely to the Orca Group; Paleogene strata in the eastern area include the Kulthieth and Poul Creek Formations and several coeval units. Environments ranging from marginal marine to bathyal and from subtropical to cool-temperate are inferred for the various molluscan faunas. Sediments range from interbedded coal and marine sands to deep-water turbidites. The known Paleogene molluscan faunas of these three southern Alaskan areas permit recognition of biostratigraphic schemes within each area, preliminary correlations between faunas of the three areas, and more general correlations with faunas of the Pacific Northwest, the Far Eastern U.S.S.R., and northern Japan.

Alaska↗
USGS2001

Fish species and community distributions as proxies for sea-floor habitat distributions: the Stellwagen Bank National Marine Sanctuary example (northwest Atlantic, Gulf Of Maine)

Defining the habitats of fishes and associated fauna on outer continental shelves is problematic given the paucity of data on the actual types and distributions of seafloor habitats. However many regions have good data on the distributions of fishes from resource surveys or catch statistics because of the economic importance of the fisheries. Fish distribution data (species or communities) have been used as a proxy for the distribution of habitats to develop precautionary conservation strategies for habitat protection (e.g., marine protected areas, fishing gear restrictions). In this study we assessed the relationships between the distributions of fish communities and species derived from trawl survey data with the spatial distribution of sediment types determined by sampling and acoustic reflectance derived from multibeam sonar surveys in Stellwagen Bank National Marine Sanctuary. Fish communities were correlated with reflectance values but all communities did not occur in unique sediment types. This suggests that use of community distributions as proxies for habitats should include the caveat that a greater number of communities within an area could indicate a greater range of habitat types. Single species distributions showed relationships between abundance and reflectance values. Trawl catches with low abundances had wide variations in reflectance values while those with high abundances had narrower ranges indicating habitat affinities. Significant non-random frequency-dependent relationships were observed for 17 of 20 species although only 12 of 20 species had significant relationships based on rank correlation. These results suggest that species distributions based on trawl survey data can be used as proxies for the distribution of seafloor habitats. Species with known habitat associations can be used to infer habitat requirements of co-occurring species and can be used to identify a range of habitat types.

Massachusetts↗
USGS1969

History of the Redwall Limestone of northern Arizona

Throughout most of northern Arizona the Redwall Limestone of Mississippian age is readily divisible into four lithologic units, designated in ascending order as the Whitmore Wash, Thunder Springs, Mooney Falls, and Horseshoe Mesa Members. The first and third members are thick-bedded to massive carbonate rock. The Horseshoe Mesa Member is relatively thin-bedded limestone, and the Thunder Springs Member is distinctive because it consists of chert beds alternating with thin beds of carbonate rock. Trends in thickness of the various members indicate that the sediment that formed the Redwall was deposited on an even, gently sloping shelf that extended westward from the Defiance positive element, a low landmass located near the present eastern border of northern Arizona. The Peach Springs and Payson ridges projected west and southwest, respectively, from the positive element. These ridges, which were partly submerged and partly above sea level during Mississippian time, are indicated by the patterns of isopach lines and, in part, by the distribution of faunas. The ridges divided the Arizona section of the shelf into three segments: the northern-most, which slopes northwest toward the Cordilleran geosyncline, and the other two, which slope toward the south and southwest. Two transgressions and two regressions of the western and southern seaways are believed to be represented by the Redwall. The first transgression, which is recorded by thick beds of clastic sediment of the Whitmore Wash Member, was less extensive than the second, which is recorded by massive beds of the Mooney Falls Member, for on the western margins of the Defiance positive element the Mooney Falls Member overlaps the two lower members. Furthermore, south of Grand Canyon the Whitmore Wash and Thunder Springs Members lap against the Payson ridge without covering it, whereas the Mooney Falls Member, although relatively thin, extends across it. Regression is believed to be represented by thin beds of the Thunder Springs and Horseshoe Mesa Members, which are interpreted to be the result of low base level caused by silting up with clastic material and consequent retreat of the sea. Cycles in sedimentation are well developed in some parts of the Redwall, especially in the upper two members in which differences in grain size represent five major cycles recognized throughout the extent of the Grand Canyon. These textural differences, ranging from aphanitic to coarse grained, are considered to be not measures of the amount of transportation, as with terrigenous sediments, but reflections of the degree of turbulence or the lack of turbulence during deposition. They are interpreted as indicators of cyclic fluctuations in environment, probably related to changes in wave base. Several clearly defined facies within the Redwall indicate environments of deposition. The clastic limestone that forms a major part of the formation, especially in the offshore areas to the west and south, is believed to represent normal marine conditions where circulation was good and turbulence moderate to strong. Uniform finely crystalline dolomite probably developed through early diagenetic processes on the sea floor. On the basis of its distribution pattern the dolomite seems to have formed under shoal conditions, especially where it borders the shore of the Defiance positive element and along Peach Springs ridge. Oölitic limestone at the top of both major transgressive units is interpreted as reflecting the oscillatory conditions of sea level that provided wave and current agitation at times of maximum sea advance in shoal areas bordering the ridges. Aphanitic limestone, representing accumulations of lime mud, seems to be developed best in the uppermost, or Horseshoe Mesa, member, where, as the seas regressed, nearshore waters may have been isolated and certainly were very calm. Original textures and some structures are preserved in most limestones of the Redwall, and they give much evidence concerning oceanographic factors of the time. Generalizations have been developed concerning the character of the bottom, degrees of energy represented, depth, salinity, and other factors for various parts of the formation. Although these factors differed greatly with time and space, the general conclusions reached are that (1) depths were very shallow to moderate, (2) the sea floor was composed nearly entirely of lime mud and lime sand, which contained no terrigeneous material but with great crinoidal accumulations locally, (3) turbulence ranged from considerable to none, and (4) the sea was clear and warm and nowhere contained saline concentrations sufficient to form evaporites. Chert forming thin irregular beds, locally lenticular and nodular, occurs at two prinicpal positions in the stratigraphic section, and in each it alternates with thin beds of carbonate rock. Chert is prominent throughout the Thunder Springs Member and forms thin but definite zones near the top of the Mooney Falls Member. This chert is believed to have formed on the sea floor during early diagenesis, as evidenced by petrography, paleogeography, and faunal relations. Regional differences in the abundance and type of associated fossils, recorded on a series of 4-foot-square sample plots made throughout the Grand Canyon, suggest a probable relation between fossil distribution and genesis of the chert. The fauna of the Redwall is abundant and varied, but preservation in many places is poor, and numerous specimens can be collected only locally. The most common fossils are brachiopods, corals, foraminifers, and crinoids, but blastoids, gastropods, cephalopods, and pelecypods are not rare. Bryozoans are abundant in the chert of the Thunder Springs Member but uncommon elsewhere. Other organisms locally distributed but not common are algae, trilobites, fish, holothurians, and ostracodes. These groups have been studied by specialists and are the subject of Chapters V through XIII. Certain of the faunal groups, notably the corals and foraminifers, show some degree of vertical zoning and so have furnished important data on age and correlation. Among the corals, the zones of Dorlodotia inconstans and Michelinia expansa are especially significant because of their persistence from section to section across broad areas. The foraminiferal zones are broader and less sharply defined, but they represent a series of major changes in species from bottom to top of the formation. Age determination made on the basis of foraminifers and brachiopods indicate that the base of the Redwall is progressively younger as it passes from areas that were offshore eastward or northward toward the Defiance positive element; the top of the Redwall, in contrast, is shown to be progressively younger away from the positive element. Thus basal beds of Kinderhook age are recognized at Grand Wash, Quartermaster, and Meriwitica Canyons to the northwest, but the lowest strata are of Osage age at Bridge Canyon, Grandview, and other sections closer to the landmass. Likewise, units with fossils of middle Meramec age occur in western Grand Canyon, but, except in the one place discussed in the following paragraph, topmost beds farther east in Grand Canyon are of Osage age. South of Grand Canyon the youngest member of the Redwall (Horseshoe Mesa) has been removed by pre-Supai Formation erosion. Rocks still younger than the Horseshoe Mesa once may have covered the entire region, possibly representing a third sequence of transgression and regression. At Bright Angel trail in eastern Grand Canyon, for example, a unique unit at the top of the Redwall section contains fossils of Chester age and apparently represents a remnant of Late Mississippian rocks that survived as an inlier there.

Arizona↗
USGS2019

Biogeographical patterns of tunicates utilizing eelgrass as substrate in the western North Atlantic between 39o and 47o north latitude (New Jersey to Newfoundland)

Colonization of eelgrass ( Zostera marina L.) by tunicates can lead to reduced plant growth and survival. Several of the tunicate species that are found on eelgrass in the northwest Atlantic are highly aggressive colonizers, and range expansions are predicted in association with climate-change induced increases in seawater temperature. In 2017, we surveyed tunicates within eelgrass meadows at 33 sites from New Jersey to Newfoundland. Eight tunicate species were identified colonizing eelgrass, of which four were non-native and one was cryptogenic. The most common species ( Botrylloides violaceus and Botryllus schlosseri ) occurred from New York to Atlantic Canada. Tunicate faunas attached to eelgrass were less diverse north of Cape Cod, Massachusetts. Artificial substrates in the vicinity of the eelgrass meadows generally supported more tunicate species than did the eelgrass, but fewer species co-occurred in northern sites than southern sites. The latitudinal gradient in tunicate diversity corresponded to gradients of summertime sea surface temperature and traditional biogeographical zones in the northwest Atlantic, where Cape Cod represents a transition between cold-water and warm-water invertebrate faunas. Tunicate density in the eelgrass meadows was low, ranging generally from 1–25% cover of eelgrass shoots, suggesting that space availability does not currently limit tunicate colonization of eelgrass. This survey, along with our 2013 survey, provide a baseline for identifying future changes in tunicate distribution and abundance in northwest Atlantic eelgrass meadows.

Connecticut, Maine, Massachusetts, New Brunswick, ↗
USGS2002

The endemic headwater stream amphibians of the American Northwest: Associations with environmental gradients in a large forested preserve

We used a large forested preserve (Olympic National Park, USA) to examine the habitat associations of a unique and environmentally sensitive stream amphibian fauna: Ascaphus truei Stegneger, Rhyacotriton olympicus (Gaige) and Dicamptodon copei Nussbaum. We quantified the relative abundance of stream amphibians and compared them to physical, topographic, climatic and landscape variables. All three species were associated with the south-west to north-east climate gradient, tending to be most abundant in the south-west. Although a habitat generalist relative to the other two species, Dicamptodon copei was absent from the north-eastern portion of the park. Ascaphus truei and Rhyacotriton olympicus were both associated with coarse substrates and steep gradients. Unlike studies in harvested forests, all stream amphibians were common in waters with unconsolidated surface geology (e.g. marine sediments that erode easily). Studies of ecological preserves can provide an important baseline for evaluating species associations with environmental gradients and can reveal patterns not evident in more disturbed landscapes.

Global Ecology and Biogeography↗
USGS2015

California State Waters Map Series — Offshore of Bolinas, California

Introduction In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow subsurface geology. The Offshore of Bolinas map area is located in northern California, on the Pacific Coast of Marin County about 10 kilometers north of the Golden Gate. The town of Bolinas, named after a local indigenous tribe, is the largest population center along this section of coast, with a population of approximately 1,600 people. Bolinas is situated at the end of a southeast-trending terrain on the west side of the San Andreas Fault that also protects a natural harbor. The harbor lies in Bolinas Lagoon, which is separated from Bolinas Bay by a spit. The coastal lands within the Offshore of Bolinas map area lie entirely within the Point Reyes National Seashore, which limits development and allows existing ranching and farming to continue. The Offshore of Bolinas map area lies offshore of the northwest-trending Coast Ranges, which lie east of, and are roughly parallel to, the San Andreas Fault Zone. The western margin of North America is the only continental margin in the world delineated largely by transform faults such as the San Andreas Fault. The coastal geomorphology is controlled by late Pleistocene to Holocene slip along the fault. Bolinas Bay and Lagoon have formed where a regional depression along the fault zone intersects the coast. A northward bend in the San Andreas Fault to the north, combined with right-lateral movement, has caused regional extension and the formation of a sediment basin on the continental shelf in, and southeast of, Bolinas Bay. With the exception of the area adjacent to Bolinas Bay, the coast in the map area consists of high coastal bluffs and vertical sea cliffs. The uplifted headland upon which the town of Bolinas is situated is part of a larger uplifted area that includes exposed bedrock offshore. Uplift in this map area has resulted in relatively shallow depths within California’s State Waters (0 to 40 m) and, thus, little accommodation space for sediment accumulation. Sediment is found in the extensional basin southeast of Bolinas, as well as on the shelf offshore of uplifted coastal areas, where, within California’s State Waters, depths can exceed 40 m. Wave energy keeps the uplifted bedrock areas clear of sediment, and rippled sediment in the outer shelf indicates some mobility. Coastal sediment transport in the Offshore of Bolinas map area is characterized by north-to-south littoral transport of sediment that is derived mainly from ephemeral streams and local coastal erosion. Beyond California’s State Waters, canyons that incise the slope have been disconnected from coastal streams by rising sea level, which has risen about 125 m since the lowstand associated with the Last Glacial Maximum about 18,000 to 20,000 years ago. In the map area, no major submarine canyons extend up past the shelf break and into the nearshore to receive littoral drift. The coastline in the map area is characterized as high risk because of its steep cliffs and large-scale landsliding. The sand spit that separates Bolinas Lagoon from Bolinas Bay is highly developed, and its homes are at risk during storms, especially those from the south. The benthic species observed in the Offshore of Bolinas map area are natives of the cold-temperate biogeographic zone named either the “Oregonian province” or the “northern California ecoregion.” This biogeographic province is maintained by the long-term stability of the southward-flowing California Current, an eastern limb of the North Pacific subtropical gyre that flows from Oregon to Baja California. At its midpoint off central California, the California Current transports subarctic surface (0–500 m deep) waters southward, about 150 to 1,300 km from shore. Seasonal northwesterly winds that are, in part, responsible for the California Current, generate coastal upwelling. The south end of the Oregonian province is at Point Conception (about 425 km south of the map area), although its associated phylogeographic group of marine fauna may extend beyond to the area offshore of Los Angeles in southern California. The ocean off central California has seen a warming over the last 50 years that is driving an ecosystem shift from the productive subarctic regime towards a depopulated subtropical environment. Seafloor habitats in the Offshore of Bolinas map area, which lies within the Shelf (continental shelf) megahabitat, range from, in the nearshore, sandy seafloor in the southeast and significant rocky outcrops that support kelp-forest communities in the northwest to, in deeper water, rocky-reef communities. Biological productivity resulting from coastal upwelling supports populations of Sooty Shearwater Western Gull, Common Murre, Cassin’s Auklet, and many other less populous bird species. In addition, an observable recovery of Humpback and Blue Whales has occurred in the area; both species are dependent on coastal upwelling to provide nutrients. The large extent of exposed inner shelf bedrock in the northeast supports large forests of “bull kelp,” which is well adapted for high wave-energy environments. Common fish species found in the kelp beds and rocky reefs include lingcod and various species of greenling and rockfish.

California↗
USGS2014

California State Waters Map Series — Offshore of Half Moon Bay, California

In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow (to about 100 m) subsurface geology. The Offshore of Half Moon Bay map area is located in northern California, on the Pacific coast of the San Francisco Peninsula about 40 kilometers south of the Golden Gate. The city of Half Moon Bay, which is situated on the east side of the Half Moon Bay embayment, is the nearest significant onshore cultural center in the map area, with a population of about 11,000. The Pillar Point Harbor at the north edge of Half Moon Bay offers a protected landing for boats and provides other marine infrastructure. The map area lies offshore of the Santa Cruz Mountains, part of the northwest-trending Coast Ranges that run roughly parallel to the San Andreas Fault Zone. The Santa Cruz Mountains lie between the San Andreas Fault Zone and the San Gregorio Fault system. The flat coastal area, which is the most recent of numerous marine terraces, was formed by wave erosion about 105 thousand years ago. The higher elevation of this same terrace west of the Half Moon Bay Airport is caused by uplift on the Seal Cove Fault, a splay of the San Gregorio Fault Zone. Although originally incised into the rising terrain horizontally, the ancient terrace surface has been gently folded into a northwest-plunging syncline by compression related to right-lateral strike-slip movement along the San Gregorio Fault Zone. The lowest elevation coincides with the deepest part of Half Moon Bay; the terrace surface rises both to the north and to the south. Uplift in this map area has resulted in relatively shallow water depths within California’s State Waters and, thus, little accommodation space for sediment accumulation. Sediment is observed in the shelter of Half Moon Bay and on the outer half of the California’s State Waters shelf. Sediment in the area is mobile, often forming dunes and sand waves. A westward bend in the San Andreas Fault Zone, southeast of the map area, coupled with right-lateral movement along the Seal Cove Fault, which comes ashore in Pillar Point Harbor, has resulted in the folding and uplifting of sedimentary rocks of the Purisima Formation in the offshore. Differential erosion of these folded and faulted layers of the Purisima Formation has exposed the parallel curved-rock ridges that are visible on the seafloor from the headland at Pillar Point. During the winter, strong North Pacific storms generate large, long-period waves that shoal and break over this bedrock reef at the world-famous surfing location known as Mavericks. The Offshore of Half Moon Bay map area lies within the cold-temperate biogeographic zone that is called either the “Oregonian province” or the “northern California ecoregion.” This biogeographic province is maintained by the long-term stability of the southward-flowing California Current, an eastern limb of the North Pacific subtropical gyre that flows from Oregon to Baja California. At its midpoint off central California, the California Current transports subarctic surface (0–500 m deep) waters southward, about 150 to 1,300 km from shore. Seasonal northwesterly winds that are, in part, responsible for the California Current, generate coastal upwelling. The south end of the Oregonian province is at Point Conception (about 365 km south of the map area), although its associated phylogeographic group of marine fauna may extend beyond to the area offshore of Los Angeles in southern California. The ocean off central California has experienced a warming over the last 50 years that is driving an ecosystem shift away from the productive subarctic regime towards a depopulated subtropical environment. Seafloor habitats in the Offshore of Half Moon Bay map area, which lies within the Shelf (continental shelf) megahabitat, range from significant rocky outcrops that support kelp-forest communities nearshore to rocky-reef communities in deep water. Biological productivity resulting from coastal upwelling supports populations of sea birds such as Sooty Shearwater, Western Gull, Common Murre, Cassin’s Auklet, and many other less populous bird species. In addition, an observable recovery of Humpback and Blue Whales has occurred in the area; both species are dependent on coastal upwelling to provide nutrients. The large extent of exposed inner shelf bedrock supports large forests of “bull kelp,” which is well adapted for high wave-energy environments. Common fish species found in the kelp beds and rocky reefs include lingcod and various species of rockfish and greenling.

California↗
USGS2015

California State Waters map series — Offshore of Scott Creek, California

Introduction In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow subsurface geology. The Offshore of Scott Creek map area is located in central California, on the Pacific Coast about 65 km south of San Francisco and 12 km northwest of Santa Cruz. The onshore part of the map area is sparsely populated; the only cultural center is Davenport, a small community with a population of less than 500. The hilly coastal area is virtually undeveloped, and a large percentage of coastal land is incorporated in open-space trusts. Agricultural land is almost entirely limited to coastal areas between the shoreline and the northwest-trending Santa Cruz Mountains, on Pleistocene alluvial fan deposits and the lowest emergent marine terrace. The Santa Cruz Mountains are part of the northwest-trending Coast Ranges that run roughly parallel to the San Andreas Fault Zone. The map area is cut by the San Gregorio Fault Zone, and it lies a few kilometers southwest of the San Andreas Fault Zone. Regional folding and uplift along the coast has been attributed to a westward bend in the San Andreas Fault Zone and also to right-lateral movement along the San Gregorio Fault Zone. The irregular coastal geomorphology of this area, which consists of low, rocky cliffs and sparse, small pocket beaches backed by low, terraced hills, is partly attributable to this ongoing deformation. The shelf in the map area is underlain by variable amounts (0 to 25 m) of upper Quaternary shelf, nearshore, and fluvial sediments deposited as sea level fluctuated in the late Pleistocene. The northernmost part of the map area is characterized by the presence of uplifted bedrock that has been linked to a local transpressional zone in the San Gregorio Fault Zone. This uplift, coupled with high wave energy, has resulted in little or no sediment cover in this area where exposures of bedrock are present at water depths of as much as 45 m. The thickest deposits of sediment lie offshore of both Davenport and the mouth of Waddell Creek. Coastal sediment transport in the map area is characterized by north-to-south littoral transport of sediment that is derived mainly from streams in the Santa Cruz Mountains and also from local coastal erosion. Shoreline-change studies indicate long-term erosion; within the region between San Francisco and Davenport, the highest long- and short-term coastal-erosion rates occur north of the map area, just north of Point Año Nuevo. During the last approximately 300 years, as much as 18 million cubic yards (14 million cubic meters) of sand-sized sediment has been eroded from the area between Año Nuevo Island and Point Año Nuevo and transported south. Once widened by this pulse of eroded sediment, beaches in the map area are now narrowing as the tail end of this mass of sand progresses farther south. The Offshore of Scott Creek map area lies within the cold-temperate biogeographic zone that is called either the “Oregonian province” or the “northern California ecoregion.” This biogeographic province is maintained by the long-term stability of the southward-flowing California Current, the eastern limb of the North Pacific subtropical gyre that flows from southern British Columbia to Baja California. At its midpoint off central California, the California Current transports subarctic surface (0–500 m deep) waters southward, about 150 to 1,300 km from shore. Seasonal northwesterly winds that are, in part, responsible for the California Current, generate coastal upwelling. The south end of the Oregonian province is at Point Conception (about 320 km south of the map area), although its associated phylogeographic group of marine fauna may extend beyond to the area offshore of Los Angeles in southern California. The ocean off of central California has experienced a warming over the last 50 years that is driving an ecosystem shift away from the productive subarctic regime towards a depopulated subtropical environment. Seafloor habitats in the Offshore of Scott Creek map area, which lie within the Shelf (continental shelf) megahabitat, range from significant rocky outcrops that support kelp-forest communities nearshore to rocky-reef communities in deeper water. Biological productivity resulting from coastal upwelling supports populations of Sooty Shearwater, Western Gull, Common Murre, Cassin’s Auklet, and many other less populous bird species. In addition, an observable recovery of Humpback and Blue Whales has occurred in the area; both species are dependent on coastal upwelling to provide nutrients. The large extent of exposed inner shelf bedrock supports large forests of “bull kelp,” which is well adapted for high-wave-energy environments. The kelp beds are the northernmost known habitat for the population of southern sea otters. Common fish species found in the kelp beds and rocky reefs include lingcod and various species of rockfish and greenling.

California↗
USGS2015

California State Waters map series — Offshore of Pigeon Point, California

Introduction In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow subsurface geology. The Offshore of Pigeon Point map area is located in central California, on the Pacific Coast about 50 km south of San Francisco and 25 km northwest of Santa Cruz. The onshore part of the map area is sparsely populated. The nearest significant onshore cultural center is Pescadero, an unincorporated community with a population of well under 1,000. The hilly coastal area is virtually undeveloped, used primarily for agricultural or as grazing land for sheep and cattle. Agriculture is limited to the coastal uplifted Pleistocene marine terraces and upper Pleistocene alluvial fan deposits, which lie between the shoreline and the northwest-trending Santa Cruz Mountains. The map area is cut by the San Gregorio Fault Zone, and is located a few kilometers southwest of the San Andreas Fault Zone. Coastal uplift and folding in the map area has been attributed to a westward bend in the San Andreas Fault Zone and also to right-lateral movement along the San Gregorio Fault Zone. The irregular coastal geomorphology of this area, which consists of low, rocky cliffs and sparse, small pocket beaches backed by low, terraced hills, is partly attributable to this ongoing deformation. The shelf in the map area is underlain by variable amounts (0 to 20 m) of upper Quaternary nearshore and shelf sediments deposited as sea level fluctuated in the late Pleistocene. The southern part of the map is characterized by the presence of uplifted bedrock that has been linked to a local zone of transpression in the San Gregorio Fault Zone. This uplift, coupled with high wave energy, has resulted in little or no sediment cover in this area where exposures of bedrock are present at water depths of as much as 45 m. The thickest deposits of sediment are located in the northern part of the map area. Coastal sediment transport in the map area is characterized by north-to-south littoral transport of sediment that is derived mainly from streams in the Santa Cruz Mountains and also from local coastal erosion. Shoreline-change studies indicate long-term erosion; within the region between San Francisco and Davenport, the highest long- and short-term coastal-erosion rates occur in the map area, just north of Point Año Nuevo. During the last approximately 300 years, as much as 18 million cubic yards (14 million cubic meters) of sand-sized sediment has been eroded from the area between Año Nuevo Island and Point Año Nuevo and transported south. Once widened by this pulse of eroded sediment, beaches south of Point Año Nuevo are now narrowing as the tail end of this mass of sand progresses farther south. The Offshore of Pigeon Point map area lies within the cold-temperate biogeographic zone that is called either the “Oregonian province” or the “northern California ecoregion.” This biogeographic province is maintained by the long-term stability of the southward-flowing California Current, the eastern limb of the North Pacific subtropical gyre that flows from southern British Columbia to Baja California. At its midpoint off central California, the California Current transports subarctic surface (0–500 m deep) waters southward, about 150 to 1,300 km from shore. Seasonal northwesterly winds that are, in part, responsible for the California Current, generate coastal upwelling. The south end of the Oregonian province is at Point Conception (about 335 km south of the map area), although its associated phylogeographic group of marine fauna may extend beyond to the area offshore of Los Angeles in southern California. The ocean off of central California has experienced a warming over the last 50 years that is driving an ecosystem shift away from the productive subarctic regime towards a depopulated subtropical environment. Seafloor habitats in the Offshore of Pigeon Point map area lie within the Shelf (continental shelf) megahabitat. Significant rocky outcrops, which support kelp-forest communities in the nearshore and rocky-reef communities in deeper water, dominate the inner shelf waters. Biological productivity resulting from coastal upwelling supports populations of Sooty Shearwater, Western Gull, Common Murre, Cassin’s Auklet, and many other less populous bird species. In addition, an observable recovery of Humpback and Blue Whales has occurred in the area; both species are dependent on coastal upwelling to provide nutrients. The large extent of exposed inner shelf bedrock supports large forests of “bull kelp,” which is well adapted for high-wave-energy environments. Common fish species found in the kelp beds and rocky reefs include lingcod and various species of rockfish and greenling.

California↗
USGS2016

California State Waters Map Series — Offshore of Santa Cruz, California

Introduction In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow subsurface geology. The Offshore of Santa Cruz map area is located in central California, on the Pacific Coast about 98 km south of San Francisco. The city of Santa Cruz (population, about 63,000), the largest incorporated city in the map area and the county seat of Santa Cruz County, lies on uplifted marine terraces between the shoreline and the northwest-trending Santa Cruz Mountains, part of California’s Coast Ranges. All of California’s State Waters in the map area is part of the Monterey Bay National Marine Sanctuary. The map area is cut by an offshore section of the San Gregorio Fault Zone, and it lies about 20 kilometers southwest of the San Andreas Fault Zone. Regional folding and uplift along the coast has been attributed to a westward bend in the San Andreas Fault Zone and to right-lateral movement along the San Gregorio Fault Zone. Most of the coastal zone is characterized by low, rocky cliffs and sparse, small pocket beaches backed by low, terraced hills. Point Santa Cruz, which forms the north edge of Monterey Bay, provides protection for the beaches in the easternmost part of the map area by sheltering them from the predominantly northwesterly waves. The shelf in the map area is underlain by variable amounts (0 to 25 m) of upper Quaternary shelf, estuarine, and fluvial sediments deposited as sea level fluctuated in the late Pleistocene. The inner shelf is characterized by bedrock outcrops that have local thin sediment cover, the result of regional uplift, high wave energy, and limited sediment supply. The midshelf occupies part of an extensive, shore-parallel mud belt. The thickest sediment deposits, inferred to consist mainly of lowstand nearshore deposits, are found in the southeastern and northwestern parts of the map area. Coastal sediment transport in the map area is characterized by northwest-to-southeast littoral transport of sediment that is derived mainly from ephemeral streams in the Santa Cruz Mountains and also from local coastal-bluff erosion. During the last approximately 300 years, as much as 18 million cubic yards (14 million cubic meters) of sand-sized sediment has been eroded from the area between Año Nuevo Island and Point Año Nuevo and transported south; this mass of eroded sand is now enriching beaches in the map area. Sediment transport is within the Santa Cruz littoral cell, which terminates in the submarine Monterey Canyon. Benthic species observed in the Offshore of Santa Cruz map area are natives of the cold-temperate biogeographic zone that is called either the “Oregonian province” or the “northern California ecoregion.” This biogeographic province is maintained by the long-term stability of the southward-flowing California Current, the eastern limb of the North Pacific subtropical gyre that flows from southern British Columbia to Baja California. At its midpoint off central California, the California Current transports subarctic surface (0–500 m deep) waters southward, about 150 to 1,300 km from shore. Seasonal northwesterly winds that are, in part, responsible for the California Current, generate coastal upwelling. The south end of the Oregonian province is at Point Conception (about 300 km south of the map area), although its associated phylogeographic group of marine fauna may extend beyond to the area offshore of Los Angeles in southern California. The ocean off of central California has experienced a warming over the last 50 years that is driving an ecosystem shift away from the productive subarctic regime towards a depopulated subtropical environment. Biological productivity resulting from coastal upwelling supports populations of Sooty Shearwater, Western Gull, Common Murre, Cassin’s Auklet, and many other less populous bird species. In addition, an observable recovery of Humpback and Blue Whales has occurred in the area; both species are dependent on coastal upwelling to provide nutrients. The large extent of exposed inner shelf bedrock supports large forests of “bull kelp,” which is well adapted for high-wave-energy environments. The kelp beds are the northernmost known habitat for the population of southern sea otters. Common fish species found in the kelp beds and rocky reefs include lingcod and various species of rockfish and greenling.

California↗
USGS2016

California State Waters map series — Offshore of Aptos, California

Introduction In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar bathymetric data (the undersea equivalent of satellite remote-sensing data in terrestrial mapping), acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow subsurface geology. The Offshore of Aptos map area is located on the Pacific Coast, on the north side of Monterey Bay, about 105 km southeast of San Francisco. The largest incorporated city in the map area, Capitola, and numerous unincorporated towns including Aptos, lie on uplifted marine terraces between the shoreline, and the northwest-trending Santa Cruz Mountains, part of California’s Coast Ranges. The map area includes the northernmost part of Santa Cruz Harbor, and Moss Landing Harbor is located about 10 km south of the map area. The offshore part of the map area is entirely within California’s State Waters and is also part of the Monterey Bay National Marine Sanctuary. In the southern part of the map area, the Soquel Canyon State Marine Conservation Area extends eastward from the limit of California’s State Waters across Soquel Canyon. The Offshore of Aptos map area is on the western margin of North American Plate—the only continental margin in the world delineated largely by transform faults. The San Andreas Fault Zone cuts through the Santa Cruz Mountains just 3.5 km northeast of the map area. The San Gregorio Fault Zone, another major plate-boundary structure, cuts through Monterey Canyon about 13 km southwest of the map area. Ongoing deformation associated with and between these major fault zones has uplifted the Santa Cruz Mountains and formed well-developed sets of marine terraces that characterize almost the entire coastal zone of the map area. The offshore part of the map area consists of relatively flat and shallow continental shelf which is underlain by variable amounts (0 to 30 m) of upper Quaternary shelf, estuarine, and fluvial sediments deposited as sea level fluctuated in the late Pleistocene. Along the southern edge of the map area, the shelf is incised by the head of Soquel Canyon, a northeast-trending tributary to the west-trending Monterey Canyon. During the last sea-level lowstand (the Last Glacial Maximum [LGM], about 21,000 years ago) Soquel Creek flowed through a paleochannel across the emergent shelf into the head of Soquel Canyon. This canyon was disconnected from its onshore watershed during the post-LGM sea-level rise of about 125 m; the abandoned paleochannel was subsequently filled with marine sediment. Coastal sediment in the Offshore of Aptos map area is supplied by coastal watersheds and bluff erosion. Sediment transport in this part of the Santa Cruz littoral cell is primarily from the northwest to the southeast and terminates in the submarine Monterey Canyon. Longshore drift is impeded by jetties at Santa Cruz Harbor, resulting in high beach erosion rates east of the harbor. Sediment dredged from the harbor mouth (estimated 300,000 yds 3 /yr) is currently being used to nourish beaches directly to the east. Farther downcoast, the rapidly eroding beach at Capitola was stabilized by construction of an about 75-m-long groin. This part of central California is exposed to large North Pacific swells from the northwest throughout the year. North Pacific swell heights range from 2 to 10 meters, with larger swells occurring from October to May. During El Niño-Southern Oscillation (ENSO) events, winter storms track farther south than they do in normal (non-ENSO) years, thereby impacting the map area more frequently and with waves of larger heights. Bedrock exposed in coastal cliffs is relatively erosion-resistant, and significant erosional events primarily are restricted to storm-wave activity that also erodes the overlying unconsolidated marine-terrace sediments. The Offshore of Aptos map area lies within the cold-temperate biogeographic zone that is called either the “Oregonian” province or the “northern California ecoregion.” This biogeographic province is maintained by the long-term stability of the southward-flowing California Current, the eastern limb of the North Pacific subtropical gyre that flows from southern British Columbia to Baja California. At its midpoint off central California, the California Current transports subarctic surface (0–500 m deep) waters southward, about 150 to 1,300 km from shore. Seasonal northwesterly winds that are, in part, responsible for the California Current, generate coastal upwelling. The south end of the Oregonian province is at Point Conception (about 310 km southeast of the map area), although its associated phylogeographic group of marine fauna may extend beyond to the area offshore of Los Angeles in southern California. The ocean off of central California has experienced a warming over the last 50 years that is driving an ecosystem shift away from the productive subarctic regime towards a depopulated subtropical environment. Seafloor habitats in the Offshore of Aptos map area lie within the “Shelf” Megahabitat class and include patchy rocky habitats, gravel-rich scour depressions, minor bedrock habitat, and predominantly sandy inner shelf. Sandy shelf habitats grade offshore to mud-dominated habitats on the midshelf in deeper water. Biological productivity resulting from coastal upwelling supports populations of Sooty Shearwater, Western Gull, Common Murre, Cassin’s Auklet, and many other less populous bird species. In addition, an observable recovery of Humpback and Blue Whales has occurred in the area; both species are dependent on coastal upwelling to provide nutrients. California sea lions and Pacific harbor seals are abundant in the map area. Common bottlenose dolphins are often observed very close to shore and in the surf zone. The large extent of exposed inner shelf bedrock supports large forests of “bull kelp,” which is well adapted for high-wave-energy environments. The kelp beds are the northernmost known habitat for the population of southern sea otters. Common fish species found in the kelp beds and rocky reefs include blue rockfish, black rockfish, olive rockfish, kelp rockfish, gopher rockfish, black-and-yellow rockfish, painted greenling, kelp greenling, and lingcod.

California↗
USGS2014

California State Waters Map Series — Offshore of San Gregorio, California

In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California's State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow (to about 100 m) subsurface geology. The Offshore of San Gregorio map area is located in northern California, on the Pacific coast of the San Francisco Peninsula about 50 kilometers south of the Golden Gate. The map area lies offshore of the Santa Cruz Mountains, part of the northwest-trending Coast Ranges that run roughly parallel to the San Andreas Fault Zone. The Santa Cruz Mountains lie between the San Andreas Fault Zone and the San Gregorio Fault system. The nearest significant onshore cultural centers in the map area are San Gregorio and Pescadero, both unincorporated communities with populations well under 1,000. Both communities are situated inland of state beaches that share their names. No harbor facilities are within the Offshore of San Gregorio map area. The hilly coastal area is virtually undeveloped grazing land for sheep and cattle. The coastal geomorphology is controlled by late Pleistocene and Holocene slip in the San Gregorio Fault system. A westward bend in the San Andreas Fault Zone, southeast of the map area, coupled with right-lateral movement along the San Gregorio Fault system have caused regional folding and uplift. The coastal area consists of high coastal bluffs and vertical sea cliffs. Coastal promontories in the northern and southern parts of the map area are the result of right-lateral motion on strands of the San Gregorio Fault system. In the south, headlands near Pescadero Point have been uplifted by motion along the west strand of the San Gregorio Fault (also called the Frijoles Fault), which separates rocks of the Pigeon Point Formation south of the fault from rocks of the Purisima Formation north of the fault. The regional uplift in this map area has caused relatively shallow water depths within California's State Waters and, thus, little accommodation space for sediment accumulation. Sediment is observed offshore in the central part of the map area, in the shelter of the headlands north of the east strand of the San Gregorio Fault (also called the Coastways Fault) around Miramontes Point (about 5 km north of the map area) and also on the outer half of the California's State Waters shelf in the south where depths exceed 40 m. Sediment in the outer shelf of California's State Waters is rippled, indicating some mobility. The Offshore of San Gregorio map area lies within the cold-temperate biogeographic zone that is called either the "Oregonian province" or the "northern California ecoregion." This biogeographic province is maintained by the long-term stability of the southward-flowing California Current, an eastern limb of the North Pacific subtropical gyre that flows from Oregon to Baja California. At its midpoint off central California, the California Current transports subarctic surface (0–500 m deep) waters southward, about 150 to 1,300 km from shore. Seasonal northwesterly winds that are, in part, responsible for the California Current, generate coastal upwelling. The south end of the Oregonian province is at Point Conception (about 350 km south of the map area), although its associated phylogeographic group of marine fauna may extend beyond to the area offshore of Los Angeles in southern California. The ocean off of central California has experienced a warming over the last 50 years that is driving an ecosystem shift away from the productive subarctic regime towards a depopulated subtropical environment. Seafloor habitats in the Offshore of San Gregorio map area, which lies within the Shelf (continental shelf) megahabitat, range from significant rocky outcrops that support kelp-forest communities nearshore to rocky-reef communities in deep water. Biological productivity resulting from coastal upwelling supports diverse populations of sea birds such as Sooty Shearwater, Western Gull, Common Murre, Cassin's Auklet, and many other less populous bird species. In addition, an observable recovery of Humpback and Blue Whales has occurred in the area; both species are dependent on coastal upwelling to provide nutrients. The large extent of exposed inner shelf bedrock supports large forests of "bull kelp," which is well adapted for high wave-energy environments. Common fish species found in the kelp beds and rocky reefs include lingcod and various species of rockfish and greenling.

California↗
USGS2000

A deep water turbidity origin for the Altuda Formation (Capitanian, Permian), Northwest Glass Mountains, Texas

The Altuda Formation (Capitanian) in the northwestern Glass Mountains is comprised of thin, even bedded limestones, dolostones, mixed clastic-carbonates, and silt/sandstones interbedded with basin-ward dipping wedge-shaped clinoforms of the Captian Limestone. The formation is characterized by graded bedding, planar laminations, flame structures, contorted/convolute bedding, horizontal branching burrows, and shelf-derived normal marine fauna. A detailed study of the Altuda Formation north of Old Blue Mountain, Glass Mountains, reveals that the formation in this area was deposited by turbidity currents in slope to basinal settings.

Texas↗
USGS2008

Devonian brachiopods of southwesternmost laurentia: Biogeographic affinities and tectonic significance

Three brachiopod faunas discussed herein record different depositional and tectonic settings along the southwestern margin of Laurentia (North America) during Devonian time. Depositional settings include inner continental shelf (Cerros de Los Murcielagos), medial continental shelf (Rancho Placeritos), and offshelf continental rise (Rancho Los Chinos). Ages of Devonian brachiopod faunas include middle Early (Pragian) at Rancho Placeritos in west-central Sonora, late Middle (Givetian) at Cerros de Los Murcielagos in northwestern Sonora, and late Late (Famennian) at Rancho Los Chinos in central Sonora. The brachiopods of these three faunas, as well as the gastropod Orecopia, are easily recognized in outcrop and thus are useful for local and regional correlations. Pragian brachiopods dominated by Acrospirifer and Meristella in the "San Miguel Formation" at Rancho Placeritos represent the widespread Appohimchi Subprovince of eastern and southern Laurentia. Conodonts of the early to middle Pragian sulcatus to kindlei Zones associated with the brachiopods confirm the ages indicated by the brachiopod fauna and provide additional information on the depositional setting of the Devonian strata. Biostratigraphic distribution of the Appohimchi brachiopod fauna indicates continuous Early Devonian shelf deposition along the entire southern margin of Laurentia. The largely emergent southwest-trending Transcontinental arch apparently formed a barrier preventing migration and mixing of many genera and species of brachiopods from the southern shelf of Laurentia in northern Mexico to the western shelf (Cordilleran mio-geocline) in the western United States. Middle Devonian Stringocephalus brachiopods and Late Devonian Orecopia gastropods in the "Los Murcielagos Formation" in northwest Sonora represent the southwest-ernmost occurrence of these genera in North America and date the host rocks as Givetian and Frasnian, respectively. Rhynchonelloid brachiopods (Dzieduszyckia sonora) and associated worm tubes in the Los Pozos Formation of the Sonora allochthon in central Sonora are also found in strati-form-barite facies in the upper Upper Devonian (Famennian) part of the Slaven Chert in the Roberts Mountains allochthon (upper plate) of central and western Nevada. Although these brachiopods and worm tubes occur in similar depositional settings along the margin of Laurentia in Mexico, they occur in allochthons that exhibit different tectonic styles and times of emplacement. Thus, the allochthons containing the brachiopods and worm tubes in Sonora and Nevada are parts of separate orogenic belts and have different geographic settings and tectonic histories. Devonian facies belts and faunas in northern Mexico indicate a continuous continental shelf along the entire southern margin of Laurentia. These data, in addition to the continuity of the late Paleozoic Ouachita-Marathon-Sonora orogen across northern Mexico, contradict the early Late Jurassic Mojave-Sonora megashear as a viable hypothesis for large-magnitude offset (600-1100 km) of Proterozoic through Middle Jurassic rocks from California to Sonora.

Special Paper of the Geological Society of America↗