Skip to main content

Late and middle Pleistocene surficial deposits

Unconsolidated to weakly consolidated alluvial fan, terrace, and basin-floor deposits with moderate to strong soil development. Fan and terrace deposits are primarily poorly sorted, moderately bedded gravel and sand, and basin-floor deposits are primarily sand, silt, and clay. (10-750 ka)
State Arizona
Name Late and middle Pleistocene surficial deposits
Geologic age Middle to Late Pleistocene
Primary rock type gravel
Secondary rock type sand
Other rock types mud; silt
Lithologic constituents
Minor
Unconsolidated > Coarse-detrital > Gravel (Fluvial)
Unconsolidated > Coarse-detrital > Gravel (Colluvial)
Unconsolidated > Coarse-detrital > Sand (Alluvial)
Unconsolidated > Coarse-detrital > Sand (Colluvial)
Unconsolidated > Coarse-detrital > Sand (Fluvial)
Unconsolidated > Coarse-detrital > Gravel (Alluvial)
Incidental
Unconsolidated > Coarse-detrital > Gravel (Mass wasting)
Unconsolidated > Coarse-detrital > Gravel (Landslide)
Unconsolidated > Coarse-detrital > Gravel (Terrace, stream)
Unconsolidated > Coarse-detrital > Sand (Eolian)
Unconsolidated > Coarse-detrital > Sand (Terrace, stream)
Unconsolidated > Coarse-detrital > Sand (Lacustrine)
Unconsolidated > Fine-detrital > Silt (Alluvial)
Unconsolidated > Fine-detrital > Silt (Fluvial)
Unconsolidated > Fine-detrital > Silt (Terrace, stream)
Unconsolidated > Fine-detrital > Silt (Lacustrine)
Unconsolidated > Fine-detrital > Silt (Eolian)
Unconsolidated > Fine-detrital > Clay (Fluvial)
Unconsolidated > Fine-detrital > Clay (Alluvial)
Unconsolidated > Fine-detrital > Clay (Terrace, stream)
Unconsolidated > Fine-detrital > Clay (Lacustrine)
Map references
Richard, S. M., Reynolds, S.J., Spencer, J. E., and Pearthree, P. A., 2000, Geologic Map of Arizona: Arizona Geological Survey Map 35, 1 sheet, scale 1:1,000,000.
Unit references
Richard, S. M., Reynolds, S.J., Spencer, J. E., and Pearthree, P. A., 2000, Geologic Map of Arizona: Arizona Geological Survey Map 35, 1 sheet, scale 1:1,000,000.
Counties Cochise - Gila - La Paz - Maricopa - Pima - Pinal - Yavapai - Yuma