The breadth of B.L. Allen’s interests in soils, geology, and the natural world are well-illustrated in continuing research on soil-geomorphology and geoarchaeology in the arid lands of the United States and Mexico. Recognizing the Time Factor in pedogenesis has proven useful in understanding how landscapes evolve. Recognizing soils buried in stratigraphic sequences further informs us regarding episodic instability (sedimentation or erosion) and stability (and soil formation) in geomorphic systems. Understanding such changes in local depositional environments may be useful in understanding regional environmental changes such as slope instability or rising water tables. Soils as time indicators and as indicators of geomorphic stability/instability are particularly invaluable in geoarchaeological research. These concepts aid in predicting presence/absence of archaeological sites and site age (e.g., advanced weathering/ pedogenesis on a landscape will indicate that "young" archaeological sites will only be found on the surface), in reconstructing occupation history (e.g., multiple occupations may form a palimpsest on old landscapes, whereas multiple, youthful buried soils could contain multiple, discrete occupation zones), in understanding site destruction and burial, and in reconstructing post-burial physical and chemical alterations of sites and artifacts. These insights are proving useful in understanding how the earliest (Paleoindian) settlers of New Mexico, Arizona, and Sonora used terminal Pleistocene landscapes.