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Pacific Northwest Geologic Mapping and Urban Hazards

Geology of Lowland aquifers

The lowland basins commonly contain important groundwater resources. In the Willamette basin of NW Oregon, the Miocene Columbia River Basalt (CRB) is a significant ground water aquifer. In this area, ground water development has gone beyond the alluvial basins and into the CRB around the basin margins. However, water flow, recharge and water quality in the basalts is controlled by complex internal stratigraphy and structure.
Northern Oregon basins map

Click to enlarge.

Although monotonous at first glance, the CRB can be mapped on a flow by flow basis using subtle variations in appearance, chemical composition, and paleomagnetic direction. We are combining field mapping, subsurface data, aeromagnetic surveys, paleomagnetic, and geochemical studies to document flow by flow stratigraphy, crustal faulting, and their role in controlling ground water resources. Our objective is to provide a modern, three dimensional model of basalt structure and stratigraphy needed to manage sustainable ground water supplies in the CRB.

Regional physiography

Geology of the Columbia River Basalt Group

Geologic Mapping

Regional overview

This site is maintained by the Pacific Northwest Urban Corridor Geologic Mapping Project, part of the Geology, Minerals, Energy and Geophysics Science Center

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