Sedimentary Rocks
Science: KS3, topic 2.5.4
Sedimentary Rocks
Sedimentary rocks are formed by deposition of small rocks and sediment.
Sedimentary rock
- Formed after the deposition of small rocks and sediment.
- Sedimentary rock is formed over millions of years.
- Sedimentary rock is built up layers.
- Fossils can be found in sedimentary rock.
Fossilisation
- A marine organism may die and fall to the ocean floor.
- If the organism doesn't rot away, it may form a fossil.
- Over time, sediment is layered on top of the organism.
Pressure and minerals
- The pressure around the organism turns the sediment to rock.
- The organism is then replaced by minerals.
Finding fossils
- We can find the fossils after the rock is weathered and eroded.
- The rock is then dug out of the ground.
- In 1957, fossils dating back to over 570 million years ago were found in Leicestershire.
Examples and their uses
- Limestone – used for making cement, buildings and making statues.
- Sandstone – used for building.
- Shale – can be used for making bricks.
Test yourself on Sedimentary Rocks
Fossilisation
What do the 570-million-year-old fossils found in Leicestershire in 1957 show about sedimentary rock?
Which of these are true of sedimentary rock?
Why can fossils last for millions of years inside sedimentary rock?