Flooding and sediment formation

In times of heavy rainfall, rivers become fast and furious and can pick up more particles from the hillsides. As the river empties into the estuary it deposits its sediments quickly and these may then form a definite layer. These layers show distinct examples of sedimentation at very different times.

Sediments can also be formed when water containing dissolved substances evaporates. This leaves substances behind as solid sediments. The remains of dead organisms are bony or have shells; they can be preserved as fossils. These fossils can be used to date the particular rock layers.

Remember the words:

heavy rainfall – сильна злива furious – оскаженілий, несамовитий

to pick up – підбирати, підхоплювати river empties into… – ріка впадає в…

estuary – гирло ріки definite – визначений, певний

layer – шар, пласт, нашарування distinct – виразний, чіткий, ясний

to evaporate – випаровувати(ся) to leave – залишати позаду

solid sediments – тверді осади remains – залишок, рештки

dead – мертвий, померлий to trap – поглинати, захоплювати

bone – кістка, bony – костистий shell – черепашка, шкаралупа

to preserve – зберігати fossil – скам’янілість, викопні рештки

to date – датувати, визначати вік particular – особливий, окремий

Answer the questions:

1. When do rivers become fast and furious?

2. What can rivers do when heavy rains fall?

3. What does the river do when it empties into estuary?

4. What do the sediments form?

5. What is the other way by which sediments can be formed?

6. What do the dissolved substances form after evaporation of water?

7. What can be trapped in sediments?

8. Which organisms can be preserved as fossils?

9. How can fossils be used?