The geology of Parrett Mountain, Oregon, and its implications on groundwater

Conference · Thu Apr 01 04:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5430568

Brodersen, B; Beeson, M ^[1]

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1. Portland State Univ., OR (United States). Geology Dept.

Parrett Mountain is a shallow SE dipping cuesta composed of Columbia River basalt that unconformably overlies Oligocene and Miocene marine sediments. The basalt has a maximum thickness of 880 feet and is composed of the Ginkgo flow of the Frenchmen Springs member of the Wanapum Basalt and the Sentinel Bluffs, Winter Water, and Wapshilla Ridge members of the Grande Ronde Basalt. The Umtanum, Ortely, and Grouse Creek members of the Grande Ronde basalt are believed to occur within the study boundaries, but, to date have not been recognized. Identification of the basalt units is based on their physical and lithologic characteristics. The local basalt groundwater system is a number of highly localized perched aquifers occurring in the Sentinel Bluffs and Winter Water basalts, along with one aquifer occurring in the Wapshilla Ridge basalt. Specific yields from the groundwater basalt aquifers range from less than half a gallon to over 50 gallons per minute. Declines in the static water levels for several small areas on the NE side of Parrett Mountain have been observed in recent years. These declines are believed to be a result of (1) commingling of water due to improperly drilled water wells, (2) the influence of the basalt stratigraphy and (3) limited recharge.

• OSTI ID: 5430568
• Report Number(s): CONF-9305259--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:5
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540250* -- Environment
Terrestrial-- Site Resource & Use Studies-- (1990-)
58 GEOSCIENCES
580000 -- Geosciences
AQUIFERS
BASALT
CENOZOIC ERA
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GEOLOGY
GROUND WATER
HYDROGEN COMPOUNDS
IGNEOUS ROCKS
INCLINED STRATA
NORTH AMERICA
OREGON
OXYGEN COMPOUNDS
PRODUCTIVITY
RECHARGE
ROCKS
TERTIARY PERIOD
USA
VOLCANIC ROCKS
WATER