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| Value | Definition |
|---|---|
| Alluvium | Unconsolidated sediment (clay, silt, sand, gravel). Includes glacial outwash deposits. |
| Dune sand | Wind deposited sand |
| Loess | Windblown silt deposits |
| Lake sediments | Lake sediments and playa deposits |
| Landslide | Landslide deposits |
| Glacial drift | Material deposited by glacial processes. Includes till and moraine (unstratified) as well as outwash (stratified). |
| Shale and mudstone | Fine-grained sedimentary rock derived from clay |
| Argillite and slate | Fine-grained metamorphic rock formed from shale |
| Tuff | Volcanic ash. Includes minor amounts of detrital sediment. |
| Siltstone | Fine-grained detrital sedimentary rock derived from silt |
| Meta-siltstone | Fine-grained metamorphic rock formed from siltstone |
| Sandstone | Medium-grained detrital sedimentary rock derived from sand |
| Meta-sandstone | Medium-grained metamorphic rock formed from sandstone |
| Quartzite | Medium-grained metamorphic rock formed from quartz-rich sandstone. |
| Conglomerate | Coarse-grained detrital sedimentary rock derived from gravel. Locally includes angular-fragment breccia. |
| Meta-conglomerate | Coarse-grained metamorphic rock formed from conglomerate |
| Carbonate | Sedimentary rock, mostly composed of limestone and dolomite, locally metamorphosed to marble. |
| Mixed miogeosynclinal rocks | Mixed sequences of miogeosynclinal sedimentary rocks. Includes interlayered shale, siltstone, lithic sandstone, quartzite, and conglomerate. |
| Mixed eugeosynclinal rocks | Mixed sequences of eugeosynclinal sedimentary rocks having abundant dark rock fragments and mafic minerals. Includes interlayered shale, siltstone, greywacke, conglomerate, and melange with subordinate mafic volcanic rock, chert, and calcareous rock. |
| Phyllite and schist | Meta-sedimentary phyllite and schist. Fine-grained metamorphic rocks derived from shale, mudstone, and siltstone. |
| Interlayered meta-sediment | Fine-to coarse-grained metamorphic rocks derived from clastic and carbonate sedimentary rocks |
| Carbonate and shale | Mixed sequences of carbonate rock and shale with subordinate sandstone and conglomerate |
| Meta-carbonate and shale | Mixed sequences of metamorphosed carbonate rock and shale with subordinate sandstone and conglomerate |
| Felsic pyroclastics | Rhyolitic pyroclastic rocks |
| Felsic volcanic flows | Rhyolitic volcanic flows |
| Calc-alkaline meta-volcanics | Calc-alkaline suite of meta-volcanic rocks |
| Calc-alkaline volcanic rocks | Calc-alkaline suite of pyroclastic rocks and volcanic flows. Generally andesite to quartz-latite. |
| Mafic pyroclastics | Basaltic pyroclastic rocks |
| Mafic volcanic flows | Basaltic volcanic flows |
| Greenstone | Mafic meta-volcanic rocks. Includes subordinate spillite, slate, argillite, and greywacke. |
| Granite | Includes intrusive rhyolitic rocks |
| Alkalic bodies | Alkalic intrusive bodies |
| Calc-alkaline intrusive rocks | Calc-alkaline suite of intrusive rocks. Generally granodiorite to diorite. |
| Mafic intrusive rocks | Generally dioritic or gabbroic |
| Ultramafic rocks | Includes associated gabbroic rocks |
| Mixed granitic gneiss | Dominantly granitic gneiss, migmatite, augen gneiss, and hornblende gneiss. Includes subordinate anorthosite, amphibolite, calc-silicate gneiss, schist, marble, and quartzite. |
| Mafic schist and greenstone | Dark-colored, fine-grained, foliated, mafic metamorphic rocks. Mostly metamorphosed basaltic to dioritic rocks. |
| Mafic gneiss | Dark-colored, medium- to coarse-grained, layered metamorphic rocks. Includes amphibolite. |
| unclassified | Unknown map units |
| open water | areas of water |
| Value | Definition |
|---|---|
| CA | California |
| CO | Colorado |
| ID | Idaho |
| MT | Montana |
| NV | Nevada |
| OR | Oregon |
| UT | Utah |
| WA | Washington |
| WY | Wyoming |
This product would not exist without the input of the many geoscientists whose work was essential to making both state geologic maps and mineral resources databases. This effort would not be possible without those past products and others from the following agencies: the US Geological Survey, the California Division of Mines and Geology, the Idaho Bureau of Mines and Geology, the Montana Bureau of Mines and Geology, the Nevada Bureau of Mines and Geology, the Oregon Department of Geology and Mineral Industries, the Utah Geological and Mineral Survey, the Geological Survey of Wyoming, and the Washington State Department of Natural Resources.
USGS geologists, Thor Kiilsgaard and Fred Miller, provided useful advice about regional geology and the identification of unlabeled features on the published state geologic maps. Art Bookstrom, Steve Box, Jim Evans, Tom Frost, and Michael Zientek, USGS geologists, contributed to the development of the major lithology classification scheme and to the classification of individual bedrock units for the map.
We particularly acknowledge Patrick Geehan, the Bureau of Land Management project coordinator for the Interior Columbia River Basin Ecosystem Management Project, for recognizing the importance of geology to ecosystem management and for supplying funds to digitize the Washington, Idaho, and Montana state geologic maps.
The goal of the ICBEMP management strategy is to provide management tools to sustain or restore ecosystem integrity and produce desired condistions, uses, products, values, and services over the long term. The intent of the project is to understand the ramifications of management practices or distrubances both in the area subject to the practice or disturbance as well as effects which may be removed, in time and space, from the area.
Are there legal restrictions on access or use of the data?Access_Constraints: None
Use_Constraints: None
This report is preliminary and has not been reviewed for conformity with US Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for desciptive purposes only and does not imply endorsement by the US Government.
| Data format: | Geologic units and structural features in format ARCE Size: 26.5 |
|---|---|
| Network links: |
http://pubs.usgs.gov/of/1995/of95-680/lithm.e00.Z |