Soil Formation

By :Reynaldo Thomas

Formation of Soil

Soil is an accumulation of tiny particles of rock which are formed when rocks are weathered.

Weathering is when rocks are broken up into smaller particles.

This happens by : 1.Physical Processes 2.Chemical Processes 3.Biological Processes

Physical /Mechanical Processes

This involves breaking rocks into smaller pieces.

Its chemical composition does not change in this process. 

Physical processes occurs as a result of:1.Water2.Ice3.Abrasion4.Temperature change

Water and ice Water expands when it form ice.

When the cracks in rocks collect water it will freeze in clod climate.

The ice will make the cracks bigger.

Hence pieces of rocks will fall away.

Abrasion

On the beach and in rivers, large rocks crash into each other.

Small particles of rock are chipped off.

Eventually the rocks get smaller and more rounded.

Temperature change

In extreme temperatures of the desert, the days are very hot and the nights are very cold.

The outer layer of rocks will crumble and fall away  (like onion layers).

Minerals in the rocks will expand and contract as the temperature changes.

This process is called exfoliation.

In regular strong winds particles of wear away larger rocks (abrasion).

This is the same effect when rubbing wood with sandpaper.

Chemical Processes

Weathering is also caused by different chemical reactions.

Weathering is also caused by chemical reactions.

The actions of carbonic acid, oxidation, dissolving and pH.

Oxygen Oxygen oxidized minerals in rocks, making

them more soluble (crumble more easily).

Dissolving Water dissolve minerals from rocks.

Forming crevices and hole.

Hence the rock structure getting weaker, making it easier for physical

weathering.

Biological Processes Biological processes is cause by plants,

animals and microorganisms.

The roots of plant expand rock crevices, which force the rock apart.

Organic acids formed from dead leaves react with minerals in rock.

Micro-organisms such as earthworms consume soil particles with food.

When passing out the particles they rubbed against each other and get smaller.