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Geology layer
The Geology layer comes straight from the U.S. Geological Survey.
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| Geology of Washington and Oregon |
Detail around Dover, NJ |
Details
Age
The smallest time period encompassing the entire range of ages in the given unit.
Note: MA = million years.
Rock
The main types of rocks in the given unit.
Name
The name of the unit.
Desc.
The full description of the unit.
Comment
Any additional comments that may be available for the unit.
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Options
Transparency
Determines how much the underlying layer(s) will show through this layer.
Color
There are two color options:
Rock type palette
When the Color by rock type option is selected, this switches between three different palettes. The first two are small variations (see above reference),
the last one was developed in-house by Integrity Logic for higher contrast.
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Origin
U.S. Geological Survey
Integrated Geologic Map Databases for the United States
These maps are available directly from the USGS.
Description of data source
Abstract
This report presents the results of the USGS Mineral Resources Program activity to compile a national-scale geologic map database at a nominal scale of 1:500,000, to support national and regional level projects, including mineral resource and geoenvironmental assessments. The only comprehensive sources for input into regional- and national-scale geologic maps are state geologic maps with scales ranging from 1:100,000 to 1:1,000,000. Digital versions of these state maps form the core of what is presented here.
Because no adequate geologic map exists for the state of Alaska, it is being compiled as regional blocks of 3 degree quadrangles that also form part of this national database. It is expected that this series will completed by approximately the end of 2007. These maps and databases are being released in blocks of states or, in the case of Alaska, as compiled blocks of 1:250,000-scale quadrangles as chapters in this series. For Alaska, formal maps as well as databases are being published here, whereas for the conterminous U.S. only state databases are presented, because published maps for most states already exist. For Alaska these regional compilations will form the base for compiling a new geologic map of the state. As documented in CONUS documentation, standards for the conterminous U.S. are somewhat different than those for Alaska and Hawaii.
Purpose
A primary goal of this work is to develop geologic map datasets with standardized structure and attribution. The database design and standards are documented in CONUS documentation of this series. The intent is that contiguous databases can be merged seamlessly and without any additional effort. In addition to a common database structure, the conterminous U.S. state databases (the contiguous 48 states) have been fitted to a set of standard state boundaries derived from the USGS Digital Line Graph 1:100,000 quadrangle boundaries (Johnson and Leveritch, 1998) so that, when states are merged, they match without slivers or overlap. No attempt has been made to reconcile differences in mapping across state boundaries.
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