Wednesday, March 27, 2013

Analysis of Rocks

1. Cuestas or Homoclinal Ridge, physical feature that has a steep cliff or escarpment on one side and a
gentle dip or back slope on the other. This landform occurs in areas of tilted strata and is caused by the
differential weathering and erosion of the hard capping layer and the soft underlying cliff maker, which
erodes more rapidly. Cuestas with dip slopes of 40°–45° are usually called hogback ridges. A mesa is an elevated area of land with a flat top and sides that are usually steep cliffs.

2. A sandur (plural sandar) is a plain formed by meltwater from glaciers. Sandar are usually wider than their length, and consist of soft sediments, which are criss-crossed by braided streams of meltwater.

3. Regolith is a layer of loose, heterogeneous material covering solid rock. Peridotite, igneous rock
composed of pyroxene, olivine, and hornblende. It is the rock that makes up the earth's mantle. Very
sudden cooling of volcanic magma results in formation of volcanic glass called obsidian. The extrusive
equivalent of granite is rhyolite & gabbro is the intrusive equivalent of basalt.

4. Entrenched & intrenched meanders are one & the same & it is ingrown meanders which grow on
assymetric valley.

5. Tephra & pyroclastic material are the same & refer collectively to volcanic materials.

6. A glacier with a negative budget is a receding glacier & that with positive budget is advancing.

7. Rectangular inselbergs are called koppie or kopje.

8. Gloup is a blow hole, where a chimney has developed behind the cliff face, often above a cave, and spray is blasted out during high seas.

9. In a braided stream, the main channel divides into a number of smaller, interlocking or braided channels. Streams with high sediment loads that encounter a sudden reduction in flow velocity generally have a braided channel type.

10. Rise of land or fall of sea level is called negative movement & is connected with rejuvenation.

11. Jura mountains were formed during Mesozoic period.

12. Researchers now recognize five glaciations in the Quaternary period: Donau, Gunz, Mindel, Riss and Wurm (in that order from old to new). Their names derive from water courses in the North Slope of the Alps. These glaciations are included in the first period of the Quaternary: the Pleistocene. The second period of the Quaternary, the Holocene, starts at the end of the last glaciation (Wurm), about 10 thousand years ago. Mindel falls under middle Pleistocene.

13. Solifluction is the slow downslope flow of soil and sediment that is saturated with water

14. Both P waves & S waves (shear, transverse) are collectively called body waves. While Surface waves include Rayleigh waves (vertical and longitudinal) & Love waves (transverse horizontal).

15. A strike slip fault is also known as wrench fault. The scientific study of rivers is called Potamology. Colluvium is the loose deposits of rock, usually located at the foot of a slope or cliff, having been brought there under the influence of gravity (mass wasting). Talus includes angular fragments of rock below cliffs and steep slopes. Colluvium includes slope wash.

16. Evidences of earliest known life have been found to archaeozoic period.

17. Victoria fall is due to faulting. Livingstone fall is at the edge of a plateau. Yosemite fall is a hanging
valley & Niagara fall is due to alternate bands of resistant & soft rocks.

18. Reg is a surface covering of coarse gravel, pebbles from which all sand and dust have been removed by wind and water.

19. Billow clouds are created when different layers of wind flow at different velocities resulting in unstable turbulence between the layers. The common name for this instability is Kelvin-Helmholtz instability. Billow clouds provide a visible signal to pilots of potentially dangerous turbulence.

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