and U.S.
ArmyEarth Science Applications, National Training Center, Fort Irw
and U.S.
Army
| UNIT/SURFACE1 | SURFACE PROPERTIES | SOILS | AGE ESTIMATE |
| Younger alluvium (Qya) and wash (Qyw) deposits: (Qya1, Qyw1) | Well-developed bar and swale topography; sparsely vegetated; loose; confined to active wash channels | None | Less than 100 years before present (yr B.P.) |
| (Qya2, Qyw2) | Well-developed bar and swale; no pavement; no varnish; moderately to sparsely vegetated; loose; 10-50 cm above Qya1; can show evidence of recent flooding | Weak A-horizon to 5 cm thick; No discernible rubification below A-horizon. | Less than 1000 yr B.P. Correlates with surface Qf5 of Wells and others (1984) and Reheis and others (1989) |
| (Qya3) | Weak bar and swale to smooth microtopography; no pavement; very weak varnish; moderately vegetated; 1 to 2 m above Qya1 and Qya2 | Weak vesicular A-horizon to 5 cm thick; weak to moderate ly developed cambic horizon to 15 cm thick; Stage I carbonate | 1000 to 8000 yr B.P.; correlates with surfaces Qf3 and Qf4 of Wells and others (1984) and Reheis and others (1989) |
| Intermediate alluvium: (Qia; Subdivided into Qia1, Qia2, and Qia3 based on inset relationships) |
Flat surfaces with moderate to strong interlocking pavements; moderate to strong varnish; weakly vegetated; 1 to 4 m above Qya1 and Qya2; 1 to 2 m above Qya3 | Moderate to strong vesicular A-horizons to 10 cm thick; moderately developed argillic horizons 10 to 40 cm thick; up to Stage II+ carbonate | May be as young as 20,000 yr B.P. based on correlation with soil on Qf1 surface of Wells and others (1984) and Reheis and others (1989); may be as old as 180,000 years based on correlation with soils in the southern Great Basin (Taylor, 1986) |
| Older alluvium and wash deposits: (Qoa, Qow) |
Rounded interfluves lacking pavement due to erosion of much of the original surface; some strongly varnished clasts as a lag left over from erosion; weakly vegetated; 1 to 5 m above Qya surfaces; often only 1 m or less above Qia surfaces | A-horizons lacking due to erosion; argillic horizon remnants rarely preserved; Stage III and weak Stage IV carbonate; surface remnant is commonly eroded completely to the calcic horizon | >250,000 yr B.P. based on correla tion with soils and surfaces in the southern Great Basin (Taylor, 1986; Peterson and others, in press) |
| Oldest alluvium: (QToa) |
Rounded surfaces similar to Qoa1 but standing as much as 25 m above Qya surfaces in western Coyote Canyon | Calcic horizons with moderate to strong Stage IV development common; upper horizons missing due to erosion | >500,000 yr B.P. based on correla tion with unit QTa in southern Great Basin (Hoover and others, 1981; Taylor, 1986) |