The slope of the sea floor greatly influences how quickly the sea floor affects the waves as the waves get closer to shore, and therefore how the waves break. A critical wave steepness occurs where the wavelength is 7 times the height of the wave and after that wave becomes unstable and breaks. There are […]
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In adjusting to change in discharge and erodibility of it’s bed, a stream modifies it’s channel so that irregularities are minimized and the least energy is expended in the movement in of water and sediments along its course. Frequently this involves enlargement of the channel cross section by erosion or reductions of it’s dimensions through
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The unstratified, unsorted debris dropped more or less randomly by the glaciers is called till. Tills can be of two types – It is laid down subglacially when debris is released directly from the sole of the ice. This involves pressure melting of basal so that debris in it is released and then lodges or
There are various forces that act upon the plates to make them move. Three possible mechanism of plate motion – Convectional Currents :- Slab Pull :- Slab pull is thought to operate at subduction zones where the subducting oceanic plate becomes colder and denser than the surrounding mantle (gabbro metamorphosed into eclogite) and pulls the
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Ichno-fossils are an expression of the alteration of the depositional fabric in sedimentary rocks by living organisms. Often these expressions are part of animal behavior or traces hence called “trace fossils”. Common structures are burrows, boring, trails and tracks. Trace fossils can be common in un-fossiliferous rocks, that can extend the geologists capability to interpret
A metamorphic facies series is a sequence of facies that occurs across a metamorphic terrane due to differences in pressure and temperature (P/T) conditions. Each facies series is characterized by the development of a particular sequence of individual facies, with each facies stable at a specific range of temperature and pressure conditions High P/T series
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Alkaline rocks occur in all tectonic environments, including the ocean basins. Alkaline rocks are generally considered to have more alkalis than can be accommodated by feldspars alone. The excess alkalis then appear in feldspathoids, sodic pyroxenes/amphiboles or other alkali-rich phases. Alkaline rocks generally occurs in three principal settings :- Some important igneous Alkaline rocks are
The structure of the Dharwar Craton is interpreted in terms of a foreland in the west and an accretionary complex in the east. The older sequence that shows a relatively higher degree of metamorphism and intrusive contact with the granitic and gneisses has been named as Sargur Group. The granitic gneisses that show intrusive contact
The Cretaceous rocks consists of thick succession of marine sequences that ranges in age from Aptian to Maastrichtian. The marine sequences represents at least four phases of marine transgression that were interrupted by brief periods of withdrawal of marine conditions. The marine transgression leads to the deposition of four groups as Dalmiapurum, Uttatur, Trichinopoly and
Cauvery Basin (Cretaceous of Trichinopoly) Read More »
