Abstract Although there is some evidence for an Eocene monsoon, the most important intensification of rainfall appears to start at c. 24 Ma in the Early Miocene. Many palaeoceanographical proxies for monsoon intensity are linked to wind and do not correlate well with humidity of the continental climate over tectonic timescales. Rainfall peaked in the middle Miocene ( c. 15 Ma) with strong drying after 8 Ma. This timing does not correlate well with either initial uplift of the Tibetan Plateau or with the retreat of shallow seas from central Asia. The c. 24 Ma onset of strengthening rainfall is associated with the initiation of rapid erosion and cooling of Himalayan metamorphic rocks. The progressive detachment of the subducting Indian lithosphere from the eastern and western syntaxes at c. 25 Ma to the east-central Himalaya at c. 13–11 Ma would have produced corresponding propagation of rising Himalayan topography following release of the weight of the detached slab. Rapid uplift of the Himalayan barrier, blocking moisture-laden winds, is considered the most likely trigger for a stronger summer monsoon in South Asia, which in turn allowed faster erosion and exhumation of the Greater Himalaya after 24 Ma.

Abstract Throughout history, if generally more conspicuously in the Old World than the New, military activities have locally and sometimes regionally shaped the face of the Earth by construction of defense works in earth or stone. Military enhancement of terrain features by fortification, scarping, or flooding to form obstacles that counter or deflect attack may thus complement the effects of natural geomorphologic agents. Military operations and exercises have polluted parts of the Earth's surface through use of explosive ordnance and by fuel leakage, and disfigured it by redundant construction works. German military geologists in particular have necessarily developed peacetime roles to protect the environment rather than the state. Yet because agricultural use and urban sprawl are restricted within the large tracts of countryside designated as military training areas, these may preserve a heritage of habitats in a fairly natural state—as valuable in terms of conservation as the many sites worldwide now preserved for their military historical record.