Allogenic Sedimentary Controls
There are three major allogenic sedimentary controls: tectonism, climate change, and eustasy. All three controls may be acting on a sedimentary basin at any one time, but they are not necessarily independent (Table 5.1). Of fundamental importance is the need to recognize a distinction between upstream and downstream controls. Upstream controls include climate and tectonics. Climate controls fluvial discharge and vegetation cover and is a major influence on sediment supply. Tectonic controls affect regional slope and the relief in the source area, and therefore are a major influence in controlling the quantity and caliber of the sediment load. The major downstream control is sea-level change, except in the case of inland basins, where the downstream control is either the level of the lake into which the river drains, or the level of the tectonic rim over which the river flows out of the basin.