Identify sedimentary rocks in the field

Sedimentary rocks can be recognised in the field by:

1. Bedding (stratification), in parallel layers of different colour or grain size.
2. Clastic texture: rounded or angular grains cemented together; gritty feel in sandstone; fine and smooth in shale.
3. Fossils (shells, plants, bones).
4. Surface marks: ripple marks, mud cracks, cross-bedding, raindrop prints.
5. Softness: often scratched more easily than igneous rocks; limestone effervesces with dilute HCl.
6. Occurrence: as layered sequences in basins and river valleys, often with pebble beds and conglomerates.