(a) Outline the characteristics… | Geography

Question 1 Report

(a) Outline the characteristics of sedimentary rocks.

(b) Describe two ways in which sedimentary rocks can be formed

Answer

Answer Details

(a) Characteristics of sedimentary rocks:

They are formed in layers (strata/beds) which are usually visible as bedding planes.
They are non-crystalline and generally softer than igneous rocks.
They frequently contain fossils of plants and animals buried during their formation.
They are made of compacted and cemented sediments (particles of pre-existing rocks or organic matter), and are often porous and permeable.
They are stratified and can be split along the layers.

(b) Two ways sedimentary rocks can be formed:

Mechanically (clastic/detrital formation): rocks are weathered and eroded into fragments; these sediments are transported by water, wind or ice, deposited in layers, then compacted and cemented over time into rock such as sandstone and shale.
Organically (biological formation): the remains of living things accumulate and are compacted, e.g. the shells and skeletons of sea organisms forming limestone/chalk, or plant remains forming coal. (Chemically formed sedimentary rocks, e.g. rock salt from evaporation, are also acceptable.)

(a) Outline the characteristics of sedimentary rocks. (b) Describe two ways in which sedimentary rocks can be formed