David's project on Rocks.

Rocks at the beach - dictated by David

When I was at the beach, I noticed the sedimentary rocks. A sedimentary rock is rock formed over millions of years, by dead plants, trees, sediment and eroded rock. The sediment goes into the rivers and gets washed to the sea. When it settles on the bottom, more sediment is packed down on top of it over millions of years. This forms into sedimentary rock.

It seemed that the rocks I saw all had holes in them. I think this is because of erosion - the weaker bits were being taken away by the wind and water.

We could tell it was sedimentary rock because there was no tinge of black or pumice. It was also nowhere near a volcano. Black rock (obsidian) and pumice are volcanic. Volcanic rock is rock that cools when it comes out of a volcano.

We also found something that appeared to be wood turning into clay or sand-stone. A bit of it was black and chipped like a branch. Another part of it looked more creamy, like clay. I think the wood was also turning into sedimentary rock. I think it got wedged into the sand at high tide, and it didn't go back out at low tide. I think it must have happened at least a year ago. It would take lots of years to harden, so I would guess it happened 50 years ago.