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P.K. Christensen

Publications and source records attributed to P.K. Christensen.

3 recordsLinked to original sources
USGS2007

Residence time of water discharging from the Hanging Gardens of Zion Park

The Hanging Gardens are a unique feature of Zion National Park. Knowledge of the source and residence time of water discharging from the Hanging Gardens is necessary to help preserve these features. Ground-water chemical and isotopic data distinguish the discharge from seeps and springs into two groups, one of low and one of high conductivity. Water with low conductivity likely originates as recharge near the steps and springs, and it only interacts with the Navajo Sandstone. High conductivity water, on the other hand, originates as recharge on the tops of plateaus to the east, where it interacts with marine rocks of the Carmel Formation. Carbon dating of these ground waters indicates that the low conductivity water is essentially modern recharge, while the high conductivity water was recharged 1,000 to 4,000 years ago.The Hanging Gardens are a unique feature of Zion National Park. Knowledge of the source and residence time of water discharging from the Hanging Gardens is necessary to help preserve these features. Ground-water chemical and isotopic data distinguish the discharge from seeps and springs into two groups, one of low and one of high conductivity. Water with low conductivity likely originates as recharge near the seeps and springs, and it only interacts with the Navajo Sandstone. High conductivity water, on the other hand, originates as recharge on the tops of plateaus to the cast, where it interacts with marine rocks of the Carmel Formation. Carbon dating of these ground waters indicates that the low conductivity water is essentially modern recharge, while the high conductivity water was recharged 1,000 to 4,000 years ago.

Water Resources Bulletin↗
USGS1993

Reconnaissance of the hydrology of sandstone and limestone aquifers along the northwest flank of the Little Rocky Mountains, Fort Belknap Indian Reservation, north-central Montana

The geohydrology of aquifers was studied the south- western part of the Fort Belknap Indian Reservation in north-central Montana. The geologic units of interest are the Lodgepole Limestone, principally composed of thin-bedded limestone; the Mission Canyon Limestone, a massive limestone containing numerous solution cavities; the lower part of the Kootenai Formation, composed of sandstone; a sands- stone unit at the base of the Colorado Group; and the Virgelle Sandstone Member at the base of the Eagle Sandstone. These units were formed during Early Mississippian through Late Cretaceous time and have been subjected to uplift, folding, and the intrusion of the igneous core of Little Rocky Mountains. Dips of these units range from nearly vertical to about 10 degrees. Thirty-one test holes were drilled and 25 of the holes were completed as monitoring wells. Water-level fluctuations in most aquifers followed a seasonal pattern with the lowest levels occurring in the fall and winter and highest levels in the spring and summer. Seasonal fluctuations ranged from about 0.6 to 21 feet. Specific capacity of wells tested ranged from 0.02 gallon per minute per foot for a well completed in the Eagle Sandstone to 4.6 gallons per minute per foot for a well completed in the Mission Canyon Limestone. Eight aquifer tests indicated transmissivity values of 15 to 1,000 feet squared per day. Dissolved-solids concentration in water collected from 22 wells ranged from 263 to 1,930 milligrams per liter. The least mineralized water was obtained from the Mission Canyon Limestone and the most mineralized from the Eagle Sandstone.

Water-Resources Investigations Report↗