Reading rocks

Drop stones

Rocks that have been dropped into sediment by icebergs

Nodules

Irregular rock formations within larger rocks

Sedimentary structures

Different shapes and patterns created in sediment by weather or natural forces

Sedimentary rocks

rocks formed by the accumulation, compaction, and cementation of sediments such as sand, mud, gravel, shells, and organic matter.

Superposition

Older layers of rock lay beneath younger layers

Horizontality

Sedimentary layers are usually deposited in flat even layers

Uniformitarianism

Processes that occurred in the past (volcanoes, earthquakes) also occur in the present

Fossil

Any bone or organic matter preserved in the geological record