BASIC GEOLOGICAL OF SOIL FORMATION

ByM. Firdaus, MT

www.dauspoli.co.cc

Rock Cycle• Grains of minerals that form the solid part of

the land is the result of weathering of rocks• Based on the original, the rocks are divided

into three types namely rock :1.Igneous rock2.Sedimentary rock3.Metamorf rock

Cycle Scheme rocksSedimenting

Sedimentary Rock

Transportation of change

Erosion

weathering

Compaction

Cementiation

Crystalize

Metamorf Rock

Metamorphosis

Melt

Igneous Rock

Magma

Igneous Rock

• Clots formed from molten magma that pushed the earth surface

• Most cooled and frozen in the rocks forming on the earth surface and partly to stop moving before it reaches the earth surface and forms an internal igneous rocks (intrusive rock)

Classification of Frozen Rocks of the texture, composition, color, and their sources

Coarse

grained

Fine

grained

Lava rocks

Granit - bright colors

Diorit – color between

Gabbro – dark colors

Riolit – bright colors

Basalt – dark colors

Obsidian – black and shiny

Batu apung – light, hollow and shiny

Skoria – reddish to black with a big empty space

Sedimentary Rock• Due to weathering processes in igneous rocks,

erosion and transportation (freight) from the products of weathering that can stay somewhere or brought elsewhere by the carrier elements such as ice, water, wind and gravity sedimentation or deposition occurs transported soil.

• Through geologic time become hard due to heavy load on it and will form the sedimentary rocks (lithification).

Classification of sedimentary rocks

• Clastic rocks, formed from differences rock grain size. Example: shale, sandstone, conglomerate

• Chemistry rock; limestone, dolomite, evaporite

• Biochemical rock / organic; Coquina, reef limestone, lime, coral, and coal

Metamorf Rock

• Formed by the process of change in composition and texture of the rocks due to heat and pressure without ever being liquid

• Rearrangement of minerals during the metamorphic rock to produce two basic texture :

1. Foliated, who produces flat rock minerals such as slate, schist2. Unfoliated, among others: quartzite, marble, and anthracite

Rock Weathering and Soil Formation

• Rock weathering is the process of the particles become smaller due to mechanical and chemical processes.

• Weathering of rocks produces the material from which the rocks were formed and produce soil. Weathering can be mechanical (physical) or chemical.

Mechanical weathering• Caused by the expanding and shrinking of the rocks

due to changes in heat and cold continuous (weather, sun, etc) that eventually destroyed the rock

• The factor is :1. Influence of climate2. Exfoliate, who berries outer exposed rocks3. Erosion by wind and rain4. Abration5. Organic activities, crushing by plants and insects that reveal

the activity of rock

Chemical weathering• Include changes in the rock minerals into new

mineral compounds. The process that occurs among other :

1. Oxidation, when the rock hit by rain2. Solution, mainly limestone partially or completely dissolve in

rain water, especially if rain water contains enough carbon dioxide.

3. Leaching, The water reacts with the adhesive material resulting in calcareous sediment of rock particles apart, forming a new sediment.

4. Hydrolisis, example the formation of clay from the weathering of which there were also water and carbonic acid formed by water that is mixed with carbon dioxide.

Transportation of products of weathering

• Weathering products can stay somewhere or other place carried by the carrier elements such as ice. Water, wind and gravity.

• Residual soil is soil which occurs by the accumulation of weathering products of just his native place only.

Classification according to type of carrier and by precipitation in a new place

• Glacial soil, formed by the transport and deposition by glaciers (rivers of ice)

• Alluvial soil, formed by transported by flowing water and deposited along streams (rivers).

• Lacustrine soil, is caused by deposition in a quiet lakes.

• Marine land, formed by deposition at sea.

• Aeolian soil, is caused by transported and deposited by wind, primarily composed of ground smooth (loess) and sand dune.

• Colluvial soil, formed by the movement of land from its original location due to gravity as it occurs in a landslide, especially lichen thalli were found at the bottom of the reef. Lichen thalli are deposits that formed at the foot of the cliffs a result of weathering on the cliff face, resulting in a pile of rock fragments at the foot of cliffs.