PHYSIOGRAPHIC REGIONS OF THE LOWER 48 UNITED STATES
LAURENTIAN UPLAND
- Superior Upland
ATLANTIC PLAIN
- Continental Shelf (not on map)
- Coastal Plain
- Embayed section
- SeaIsland section
- Floridian section
- EastGulf Coastal Plain
- Mississippi Alluvial Plain
- WestGulf Coastal Plain
APPALACHIAN HIGHLANDS
- Piedmont province
- Piedmont Upland
- Piedmont Lowlands
- Blue Ridge province
- Northern section
- Southern section
- Valley and Ridge province
- Tennessee section
- Middle section
- HudsonValley
- St. Lawrence Valley
- Champlain section
- Northern section (not on map)
- Appalachian Plateaus province
- Mohawk section
- Catskill section
- Southern New York section
- AlleghenyMountain section
- Kanawha section
- Cumberland Plateau section
- CumberlandMountain section
- New EnglandProvince
- Seaboard Lowland section
- New England Upland section
- White Mountain section
- GreenMountain section
- Taconic section
- Adirondack province
INTERIOR PLAINS
- Interior Low Plateaus
- Highland Rim section
- Lexington Plain
- NashvilleBasin
- Central Lowland
- EasternLake section
- WesternLake section
- Wisconsin Driftless section
- Till Plains
- Dissected Till Plains
- Osage Plains
- Great Plains province
- Missouri Plateau, glaciated
- Missouri Plateau, unglaciated
- Black Hills
- High Plains
- Plains Border
- ColoradoPiedmont
- Raton section
- PecosValley
- EdwardsPlateau
- Central Texas section
INTERIOR HIGHLANDS
- Ozark Plateaus
- Springfield-Salem plateaus
- Boston"Mountains"
- Ouachita province
- ArkansasValley
- Ouachita Mountains
ROCKY MOUNTAIN SYSTEM
- Southern Rocky Mountains
- WyomingBasin
- Middle Rocky Mountains
- Northern Rocky Mountains
INTERMONTANE PLATEAUS
- Columbia Plateau
- Walla Walla Plateau
- BlueMountain section
- Payette section
- Snake River Plain
- Harney section
- Colorado Plateaus
- High Plateaus of Utah
- UintaBasin
- Canyon Lands
- Navajo section
- Grand Canyon section
- Datil section
- Basin and Range province
- Great Basin
- SonoranDesert
- Salton Trough
- Mexican Highland
- Sacramento section
PACIFIC MOUNTAIN SYSTEM
- Cascade-SierraMountains
- Northern Cascade Mountains
- Middle Cascade Mountains
- Southern Cascade Mountains
- Sierra Nevada
- Pacific Border province
- Puget Trough
- Olympic Mountains
- OregonCoastRange
- KlamathMountains
- California Trough
- CaliforniaCoast Ranges
- Los AngelesRanges
- Lower California province
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A Tapestry of Time and Terrain:
The Union of Two Maps - Geology and Topography
Rocks of Ages:
An explanation of the legend
Geologists subdivide time variously by eras (Precambrian to Cenozoic), periods (Cambrian to Quaternary), and epochs - only Pleistocene (early Quaternary) and Holocene (late Quaternary) are used here (see column at left). These units are quite uneven in elapsed time, the older intervals generally being of much longer duration. Rocks in the U.S. range in age from early Precambrian (2.6 billion years ago) to Holocene, which includes the present. The orderly sequence of Earth materials, from oldest to youngest, is represented by an equally well-ordered sequence of "prismatic" colors (based on the rainbow). To improve the color balance of the tapestry, the Holocene is represented by two hues, light gray in the East and beige in the West.
The King and Beikman geologic map of the U.S. was compiled from many detailed maps that describe the rocks of smaller areas. The constituent maps were made by many individuals from field and laboratory observations. These geologic maps distinguish among types of rocks that form in different ways: igneous granite and basalt; sedimentary sandstone, shale, and limestone; and metamorphic slate, marble, gneiss, and schist. From several converging lines of evidence - fossils, the layered sequence of strata, and the systematic radioactive decay of certain minerals - geologists have been able to place the rock formations in their correct time order, and from that arrangement construct a sequence of likely geologic events.