River terraces (tectonic–climatic interaction)

There is a delicate equilibrium that controls a river system, which, when disturbed, causes flooding and incising events to occur and produce terracing.

Currently used techniques are magnetostratigraphy, low temperature thermochronology, cosmogenic nuclides, radiocarbon, thermoluminescence, optically stimulated luminescence, and U-Th disequilibria.

Evaluation on geologically short time scales (103-105 a) can reveal much about the relatively shorter climatic cycles,[5] local to regional erosion, and how they could drive terrace development.

In many cases, simplifying the geologic issue to tectonic-driven vs. climate-driven is a mistake because tectonic-climate interactions occur together in a positive feedback cycle.

Rivers in continental interiors that have not experienced tectonic activity in the geological recent history likely record climatic changes through terracing.

The Milankovitch cycles, along with solar forcing, have been determined to drive periodic environmental change on a global scale, namely between glacial and interglacial environments.

Although these surfaces formed at sea level maxima during interglacial periods, the landforms are preserved solely due to tectonic uplift.

One of the greatest examples of this feedback between tectonic and climatic interactions may be preserved in the Himalayan front and in the development of the rain shadow effect and the Asian Monsoon.

[7][8][9] Tectonic uplift during the creation of high mountainous regions can produce incredible surface elevations and therefore exposure of rocks to wind and water.

Buoyancy of the crust, or isostasy, will then drive further tectonic uplift, in order to achieve equilibrium, as sediment is continuously stripped from the top.

A series of terraces along a river. The oldest terraces (T1) are higher standing than the younger terraces (T3). The present floodplain (T4) will soon become the youngest terrace surface as the river incises.
The Rio Grande, flowing down through the Rio Grande Rift for the last several million years. The last stage of incision by the river is thought to be driven by the Milankovitch eccentricity cycle. Increased precipitation and sediment supply drove incision of the high standing terraces, beginning at ~800ka. [ 1 ]
A schematic diagram of the morphology of coastal/marine terraces. Periodic uplift will force old shorelines up, which create the terrace treads. Wave erosion on these old shorelines will produce the scarp, or terrace riser.
A satellite image of the Himalayas and the rainshadow effect. Development of the Himalayan front and South Asian Monsoon is thought to be driven by tectonic-climatic interactions.