Figure 3: Loess in a 3-meter deep backhoe trench near Idaho Falls showing surface soil horizons. The Bk horizon is white because of the buildup of calcium carbonate in the semi-arid climate. A buried soil horizon (paleosol) is present near the base of the trench indicating that several periods of loess deposition have occurred. Optically stimulated luminescence (OSL) dating is used to measure elapsed time since last exposure of the loess to sunlight. OSL ages from the C horizon in the trench range from 17.5 ka to 21.9 ka, while those below the paleosol are 75.3 ka.
Image 17223 is a 1601 by 1201 pixel WebP
Uploaded:
Oct30 09
