There is no general theory of geomorphology. We cannot cast the subject in a single equation, or set of equations. As with geology, geomorphology is a tangle of physics, chemistry, biology and history. It is also geometry, as the geomorphology plays out in a complex geographic, topographic setting in which both the tectonic and climate processes responsible for driving evolution of the topography change in style and intensity. There is no grand quest for a Universal Law of Geomorphology. Our subject is often subdivided according to the geographic elements of the geomorphic system: hillslopes, rivers, eolian dunes, glaciers, coasts, karst, and so on.
There is indeed order to the natural system on and near the earth’s surface that
in turn serves to connect these subdisciplines. Features in common among many
geomorphic realms include:
• Surface materials most often move in one direction: downhill, downstream, downdrift,
or downwind. (Prior to emergence on the surface, the motion is effectively
vertical, in the reference frame of the surface, during near-surface exhumation.)
• Materials are transformed as they move through the system. Some of this is again
unidirectional, this time meaning irreversible: large grains can be broken into small
grains, but not the reverse; chemical reactions are for the most part permanent, resulting in solutional loss and change in mineralogy toward low temperature hydrous phases.
Exceptions to this general statement do exist: duricrusts form by cementation of soils, and carbonate deposits accumulate.
• Motion is concentrative. Material gathers itself into more efficient streams (Shreve’s
dichotomy of hillslopes and streams (Shreve, 1979)) resulting in spatially-branching
networks. This is one of several instances in which the surface processes lead to selforganization.
• If given enough time, the system evolves toward a state in which the material flow is
adjusted to transport that supplied to it.
These features argue for some degree of universality in our subject, some degree of connection between the elements of landscape and our treatment of those elements. The
most useful scientific principle that we will employ here is that of conservation: conservation of mass, of energy, and momentum. “mass is conserved” or “energy is conserved”. These are indeed fundamental laws of physics. And physicists lean on them heavily. So also is momentum conserved, and angular momentum. So also is baryon number, strangeness, and so on. The fact that on the earth’s surface the speeds involved are far less than the speed of light allows us to dodge the complexity introduced by Einstein; we can go right back to Newton. As we do not need to worry about the conversion of mass to energy, mass is conserved perfectly.
Its been 70 years since we are living in an vibrant Independent nation. Perhaps it is high time to uphold individual freedom and take a pledge to do all to keep it s flag high.
Though I hate to repeat myself but perhaps it is need of the hour. I am taking words from an older post of mine here.
“Salawatein zaroori nahee hein. Light a candle; stop cursing the darkness. Don’t IGNORE the darkness. Understand the darkness, know its causes; work to fix them. But don’t waste precious, precious bandwidth just chanting against it.
Salawatein zaroori nahee hein.
Let all of us light a candle and pray for the right path and peace to the mankind.”
Here is an admirable spirit of Independence Day. Someone shared it on whatsapp.
And some second thoughts:
Here is some views from Sabahat
Independence Day? Yes, let us mark the Day(s); let us commemorate and even celebrate. But in countries with over 50% child abuse rates, poverty, and a thirst for something better, something more than survival–and in a region that damn near invented meditation, maraqba, dhyana yoga, zen, instead of a “Happy Independence Day”, could I call for an Meditative Independence Day? One full of thought, and introspection…and, above, all, meditating, contemplating the meaning of the word “Independence”? I am not going to challenge that the middle of August 1947 brought independence. But how can we be MORE independent? Free from outside exploitation. And from internal exploitation. Free from fear. Free from want. Free to want what we want. Free to know. Free, above all, to think and to see.
No analysis is considered complete without conflicting voices 🙂
See this video also
Diastrophism, also called tectonism, large-scale deformation of Earth’s crust by natural processes, which leads to the formation of continents and ocean basins, mountain systems, plateaus, rift valleys, and other features by mechanisms such as lithospheric plate movement ( plate tectonics), volcanic loading, or folding.
All processes that move, elevate or build up portions of the earth’s crust come under diastrophism. They include: (i) orogenic processes involving mountain building through severe folding and affecting long and narrow belts of the earth’s crust; (ii) epeirogenic processes involving uplift or warping of large parts of the earth’s crust; (iii) earthquakes involving local relatively minor movements; (iv) plate tectonics involving horizontal movements of crustal plates.
There are various theories of the cause of diastrophic movement such as being the result of pressures exerted by convection currents in the mantle or the rise of magma through the crust. Other deformations are caused by meteorite impact and combinations of gravity and erosion such as landslides and slumping.
The study of diastrophism encompasses the varying responses of the crust to tectonic stresses. These responses include linear or torsional horizontal movements (continental drift by Alfred Wegner) and vertical subsidence and uplift of the lithosphere (strain) in response to natural stresses on Earth’s surface such as the weight of mountains, lakes, and glaciers. Subsurface conditions also cause subsidence or uplift, known as epeirogeny, over large areas of Earth’s surface without deforming rock strata. Such changes include the thickening of the lithosphere by overthrusting, changes in rock density of the lithosphere caused by metamorphism or thermal expansion and contraction, increases in the volume of the asthenosphere (part of the upper mantle supporting the lithosphere) caused by hydration of olivine, and orogenic, or mountain-building, movements.
Source(s) and Links:
Seismic Waves and Earth Interior