3: Describing Sediment and Sedimentary Rocks
The size, shape, and composition of particles are the most important characteristics for the description and classification of sediment and sedimentary rock. Specific characteristics include particle size and size distribution, grain shape and the nature of any edges, and the maturity of a sample as recorded by the composition of framework grains and interstitial material.
- Classify sediment and sedimentary rocks using an Udden-Wentworth grain size chart
- Convert between millimeters and phi units
- Describe grains using sorting and rounding terminology
- Discuss how composition and/or grain size is used to classify sedimentary rocks and provide examples
- Describe specimens using the concepts of compositional and textural maturity and make general interpretations about what these properties record in terms of environments and processes.
Cover diagram shows a stylized portrayal of an immature sandstone ( Page Quinton via Wikimedia Commons ; CC BY-SA 4.0 ).