9696/13/O/N/21

Rocks and weathering 3 Fig. 3.1 is a photograph which shows a weathered rock in Colorado, USA.

(a) Name the type of weathering shown in Fig. 3.1. [1]

Vegetation root action

(b) Describe the main characteristics of the weathered rock shown in Fig. 3.1. [3]

• The rock has joints and cracks due to weathering

MS

The main points that could be noted are: • Main root extending into large crack • Other cracks developing as a result of the root action • Blocky jointing in the rock • Lichens on rock surface/coniferous trees • Red in colour/oxidised

(c) Explain how the Peltier diagram helps geographers to understand weathering in different environments. [6]

MS:

The main points are: • Weathering types are related to precipitation amounts and temperatures • Intensity of weathering is shown • Environments where there is a combination of weathering types are identified • It enables the role of temperature and precipitation to be assessed with respect to the different weathering processes, and allows weathering classification Development points could relate to freeze thaw, exfoliation, etc., and accentuation of chemical weathering at high temperatures and in areas of high precipitation. 1 mark for a simple explanation, 2 marks for a developed explanation and 3 marks for a well developed explanation up to the maximum. Credit valid diagram.