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Chalk is so common in Cretaceous marine beds that the Cretaceous Period was named for these deposits. The name Cretaceous was derived from Latin creta, meaning chalk. [10] Some deposits of chalk were formed after the Cretaceous. [11] The Chalk Group is a European stratigraphic unit deposited during the late Cretaceous Period.
The products of chalk weathering are dissolved in rainwater and are transported in stream flow. Chalk streams transport little suspended material (unlike most rivers), but are considered "mineral-rich" due to the dissolved calcium and carbonate ions. The surface water of chalk streams is commonly described as "gin clear".
The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related terms include aquitard , which is a bed of low permeability along an aquifer, and aquiclude (or aquifuge ), which is a solid, impermeable area underlying or overlying an aquifer, the pressure of which could lead to the formation of a ...
Syneresis cracks form in a similar way, with the exception that they are never exposed to air, instead being caused by changes in the salinity of the surrounding water. Raindrop impressions form on exposed sediment by raindrop impacts. Parting lineations are subtly aligned minerals that form in the lower part of the Upper Flow Regime within ...
On an average day nearly 303 million US gallons (1,150,000 m 3) of water flow from Big Spring in Missouri at a rate of 469 cubic feet per second (13.3 m 3 /s). Grand Prismatic Spring, Yellowstone National Park, Wyoming. A spring is a natural exit point at which groundwater emerges from an aquifer and flows across the ground surface as surface ...
The fall of water where the stream goes over a sudden drop called a knickpoint; some knickpoints are formed by erosion when water flows over an especially resistant stratum, followed by one less so. The stream expends kinetic energy in "trying" to eliminate the knickpoint. Wetted perimeter
Wind, ice, water, and gravity transport previously weathered surface material, which, at the loss of enough kinetic energy in the fluid, is deposited, building up layers of sediment. This occurs when the forces responsible for sediment transportation are no longer sufficient to overcome the forces of gravity and friction , creating a resistance ...
A dry valley may develop on many kinds of permeable rock, such as limestone, chalk, sand stone and sandy terrains that do not regularly sustain surface water flow. Such valleys do not hold surface water because it sinks into the permeable bedrock. There are many examples of chalk dry valleys along the North and South Downs in Southern England.