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Preston E. Cloud

Publications and source records attributed to Preston E. Cloud.

5 recordsLinked to original sources
USGS1959

Part 4. Submarine topography and shoal-water ecology

The topography of the sea floor within 10 miles of Saipan broadly resembles that of the land. Eastward, toward the Mariana trench, slopes are about 6°, without prominent benches or scarps. This is inferred to indicate easterly continuation of generally pyroclastic bedrock. The westward slope averages 2° to 3° and consists mainly of nearly flat benches and westfacing scarps. This is taken to imply westward continuation of a limestone bench-and-fault-scarp topography. Projection of known faults to sea and through Tinian, on the basis of topographic trends, suggests a pattern of west-dipping normal faults that parallel the strike of the Mariana ridge and affect the shape and position of islands at the crest of the ridge.

Professional Paper↗
USGS1956

Geology of Saipan, Mariana Islands; Part 1, General geology

Saipan, situated about 15° N. and 146° E., is one of the larger and more southerly of the Mariana Islands. The 15 small islands of this chain are strung along an eastwardly convex ridge for more than 400 miles north to south, midway between Honshu and New Guinea and about 1,200 miles east of the Philippines. Paralleling this ridge 60 to 100 miles further east is a deep submarine trench, beyond which lies the Pacific Basin proper. To the west is the Philippine Sea, generally deeper than 2,000 fathoms. The trench coincides with a zone of negative gravity anomalies, earthquake foci occur at increasing depths westward from it, and silica- and alumina-rich volcanic rocks characterize the emergent island chain itself. The contrast between these features and those of the Pacific Basin proper to the east is held to favor the conclusion that the Mariana island arc and trench define the structural and petrographic front of Asia

Saipan↗