The architecture of a basin can be described as the geometry and relative arrangement of the major facies assemblages in the basin fill. It reflects basin shape, subsidence rates and the position of major sediment sources. Most of these parameters are governed by tectonics.
Miall (1981b) showed that in most alluvial basins the drainage network has an orthogonal relationship to local tectonic grain. The main drainage from surrounding source areas descends a paleoslope oriented perpendicular to the main controlling tectonic elements.
These transverse rivers may drain into a lake at the basin centre or into the sea. Alternatively the centre of the basin may be occupied by a trunk river flowing along the basin axis as a longitudinal river.
Transverse rivers may include a belt of alluvial fans (bajada) at the basin margin. They form alluvial plains or piedmonts tens to a few hundreds of kilometres in width. Longitudinal drivers may be hundreds to thousands of kilometres long. All the world's major rivers (Amazon, Nile, Mississippi, Ganges, Brahmaputra etc.) are longitudinal.
Rivers end as estuaries, or as deltas, or as ephemeral channels dying out on lake margins or tidal flats. Deltas may conveniently by classified into three types, reflecting the predominance of either fluvial, wave or tidal energy as the main sediment dispersal mechanism on the delta front (Galloway, 1975). River dominated deltas build out a birdsfoot or lobate pattern unimpeded by marine dispersal processes. In areas of high wave energy the river-borne sediment is carried