GEOLOGY LECTURE # 3

Plutonic rocks:

Plutonic rocks are formed when magma cools slowly at great depth with the retention of the volatiles. The texture of such rocks is coarse grained.

 Fissure:

A long ,narrow opening or line of breakage made by cracking or splitting, especially in rock or earth. Usually if opening b/w rock is more than 1 m then it will b called as fissure.

Joint:

A crack or fracture present in a rock is called joint. It may be vertical horizontal or inclined joint.

Faults:

A fault is a fracture along which there has been relative displacement of beds(a small litho-logical unit is called as bed).

Volcanic eruption:

The process in which the hot lava or volcanic gases comes out from a vent or fissure in the earth crust is called volcanic eruption .

Geo hazards:

"Geo hazards" are events caused by geological features and processes that cause severe threats to humans and the natural environment. Earthquakes, floods, landslides, volcanoes, avalanches, are typical examples of such events.

Fields related to geology:

1.geological engineering        2.engineering geology

 3.geotechnology                    4.geomechanics

5.tunnels                                 6.bridges

7.dams                                                8.canals

9.drains                                   10.river

11.rock slopes                         12.ports or harbors

13.foundation                          14.earthquakes                       15.ground water

Classification of igneous rocks:

Texture (essential +- accessory)	Orthoclase and quartz +- plagioclase, biotite & muscovite	Plagioclase and hornblende+- biotite, quartz, augite.	Plagioclase and augite+-olivine, hornblende	Pyroxene + hornblende	Olivine +- pyroxene
Coarse crystalline(plutonic)	Granite	Diorite	Gabbro	Peridotite	Dunite
Coarse crystalline with phenocrysts.	Pegmatatic granite	Rare or unknown	Rare or unknown	Rare or unknown	Rare or unknown
Volcanic fluid or micro crystals	Rhyolite	Andesite	Basalt	Rare or unknown	Rare or unknown
Fine  crystalline with large crystals	Porphyritic rhyolite	Porphyritic andesite	Prphyritic basalt
Galaxy	Obsidian	Rare or unknown	Rare or unknown	Rare or unknown	Rare or unknown
vasicular	Pumice		Vasicular basalt