Students MUST know sequence of sedimentary rock formation:

1. Weathering and erosion of existing rock.

2. Deposition of eroded rock particles.

3. Compaction of deposited particles by overlying sediments or water and sediments.

4. Cementation of compacted particles by precipitated minerals.

Sedimentary rocks are formed from the remains of older rocks that have been worn away.

Layer upon layer of rock pieces may be gathered together in one place by water, wind or ice. Many were originally part of the sea bed and also contain fossils of shells and tiny sea creatures. Over thousands of years, the weight of the layers above presses the bottom layers together so hard that they join together into solid rock again. It’s a bit like squeezing damp soil together to make a solid ball.

Sedimentary rocks:

• Conglomerate
• Limestone
• Sandstone
• Chalk

Sedo is Latin for settle down. Sedimentary rocks are formed, remember, when the remains of other rocks are deposited (laid down) as sediments. Chalk, for example, is the slow build-up of the skeletons of millions, billions, zillions of tiny sea creatures.