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(Technical Report No. 45)

J.M. Gray¹ and B.W. Murphy²  

(¹Soil Information Systems Unit, Parramatta; Ecosystem Management Unit, Cowra)

1999

This publication appears in its entirety on this website in small, easily downloaded chapters (click on the Contents link). The authors' acknowledgements appear below (follow the link).

Alternatively, the publication can be e-mailed to you as a single pdf document of 3190Kb by contacting the authors. If requesting this publication as a single pdf for e-mailing, please ensure that this does not exceed the message size limit of your ISP. Parent Material and Soil may also be purchased as a hard copy publication (Aus$20.00 including GST, plus postage and packaging) from the Department of Infrastructure, Planning and Natural Resources' Information Centre.

Introduction | Contents | Acknowledgements

Introduction

Parent material has a major influence on the physical and chemical make-up of soils. It is a significant controlling factor of soil properties at most sites, being one of the five traditionally recognised factors of soil formation, along with climate, topography, organic matter and time. One early worker, giving his view of the importance of parent rock, described soil as a ‘kind of pathologic condition of the native rock’ (Rickthofen 1882, in Joffe 1949 - PDF 62KB).

Parent material may be considered as predominantly comprising either primary in-situ bedrock or secondary transported material (such as alluvium, colluvium, aeolian or glacial deposits). This report is primarily directed towards parent material in the form of relatively unweathered in-situ bedrock but the principles outlined can be equally applied to other parent materials such as alluvium, providing there is knowledge of the broad chemical and physical composition of these materials.

Broadly speaking, the report attempts to outline how and why parent material influences soil distribution and soil properties. It also gives an indication of the likely soil types and soil properties formed from different parent materials under various climatic and drainage conditions experienced in eastern Australia (excluding the extreme climatic zones).

More specifically, the report covers the following matters:

• overview of the main soil forming factors (section 2);
• overview of the classification of parent material, in terms of both traditional geological purposes and for pedologic purposes, together with tables giving standard chemical compositions (section 3);
• outline of the main characteristics of parent material that influence soil properties (section 4);
• summary of how specific soil properties such as fertility, texture and erodibility are influenced by parent material (section 5);
• detailed description of soil properties and soil types expected from different parent materials under different rainfall and drainage regimes. These descriptions are supported by charts derived from an analysis of over 8000 soil samples stored in the DIPNR NSW Soil and Land Information System (section 6);
• summary charts and figures which attempt to graphically delineate the relationship between soil types (using Great Soil Groups and Australian Soil Classification) and the three parameters of parent material, annual rainfall and drainage (section 7);
• some common causes of uncertainty involved in the use of information on parent material for predicting soil properties (section 8);
• provided in the Appendices are two charts showing the correlation between soils of different soil classification schemes (Appendices 1a and 1b), six sample profiles of major soil types formed on different parent materials under different environmental regimes (Appendix 2) and a simple key to assist in the identification of the more common rocks found in eastern Australia (Appendix 3).

It is stressed that due to the complexities of soil development the predictions outlined in this report will not be applicable in all situations. The report is primarily intended as an aid to the development of soil distribution models over a region or at a site. It can be used as a basis for hypothesis generation in soil mapping and to provide a first approximation of likely soil properties at a particular site, but any resulting predictions should be checked in the field before being relied upon.

The report is directed to both soil professionals, chiefly those involved in soil mapping, and to a range of other natural resource professionals who may require information on soils at a site in situations where there are no detailed soil maps available.

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Contents

1. Introduction

2. Factors of Soil Formation (PDF 550KB) (including 2.1 Parent Material, 2.2 Climate, 2.3 Topography, 2.4 Organic Activity, 2.5 Time)

3. Classification of Parent Material (PDF 363KB) (including 3.1 Standard Geological Classification of Parent Material, 3.2 Broad Classification of Parent Material for Pedologic Purposes)

4. Properties of Parent Material that Influence Soils (PDF 113KB) (including 4.1 Mineralogical and Chemical Composition, 4.2 Physical Properties)

5. The Influence of Parent Material on Specific Soil Properties (PDF 75KB) (including 5.1 Chemical Fertility, 5.2 Texture, 5.3 Structure, 5.4 Sodicity, 5.5 Erodibility, 5.6 Acidity, 5.7 Acid Sulfate Potential, 5.8 Shrink/swell and Related Phenomena, 5.9 Thickness and Rock Outcrop)

6. Modelling of Soil Distribution based on Parent Material and Environment (PDF 1.5MB) (including 6.1 Extremely Siliceous Parent Material, 6.2 Highly Siliceous Parent Material , 6.3 Transitional Siliceous/Intermediate Parent Material, 6.4 Intermediate Parent Material, 6.5 Mafic Parent Material, 6.6 Ultramafic Parent Material, 6.7 Calcareous Parent Material, 6.8 Alluvial Parent Material, 6.9 Organic Parent Material, 6.10 Sesquioxide Parent Material)

7. Summary of Soil Distribution Charts (PDF 545KB) (including 7.1 Extremely Siliceous Parent Material, 7.2 Highly Siliceous Parent Material, 7.3 Transitional Siliceous/Intermediate Parent Material, 7.4 Intermediate Parent Material, 7.5 Mafic Parent Material, 7.6 Ultramafic Parent Material, 7.7 Calcareous Parent Material, 7.8 Alluvial Parent Material, 7.9 Organic Parent Material, 7.10 Sesquioxide Parent Material)

8. Causes of Uncertainty (PDF 36KB)

9. Conclusion (PDF 33KB)

10. References (PDF 62KB)

Appendices:

Appendix 1A (PDF 64KB): Approximate Correlation Between the Australian Soil Classification and Other Schemes

Appendix 1B (PDF 55KB): Australian Soil Classification Orders and Broad Correlation with Great Soil Groups

Appendix 2 (PDF 176KB): Soil Profiles from Various Parent Materials and Environments

Appendix 3 (PDF 106KB): Key to the Identification of Common Rocks

Appendix 4 (PDF 85KB): Major Australian Soils - Main Diagnostic and Land Management Features

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Acknowledgements

The authors, Jonathan Gray and Brian Murphy, wish to acknowledge the people who contributed towards this project.

Peter Smith is thanked for his role in the initiation of the project and, together with Neil Abraham, for constant support and assistance. Dr Philip Ryan is thanked for his detailed final review and comments and Peter Charman for his final technical editing and suggestions.

A number of other people provided useful comments and suggestions throughout the project, including soil scientists Greg Chapman, Glenn Atkinson, Mitch Tulau, Casey Murphy, Humphrey Milford, Robert Banks and Dave Morand and also Dr Colin Pain (AGSO) and Dr John Field (ANU). Other officers, including Susan Abraham, Nargis Banu, Anne-Marie Mills, Andrea Francis and Andrew Rawson provided valuable data and assistance.

This report should be cited as:

Gray, J.M. and Murphy, B.W. 1999, Parent Material and Soils - A Guide to the Influence of Parent Material on Soil Distribution in Eastern Australia, Technical Report No. 45 (Reprinted 2002), NSW Department of Land and Water Conservation, Sydney. ISSN 1324 - 6860.

Crown © 1999 NSW Department of Natural Resources. Parts may be reproduced for the purpose of study and/or research provided acknowledgement of the source is clearly made.

Further information on the Department of Natural Resources' soils program may be obtained from the soils website or by emailing soils@dnr.nsw.gov.au.

This website version of Parent Material and Soils was prepared in 2003 and contains minor corrections to the printed version, together with the addition of Appendix 4.

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Last modified: 18/05/2004
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