Exercise1. Use the correct tense forms of the verbs. All sentences refer to the future.

1. The river will become fast and furious if a heavy rain (to fall).

2. When the river becomes fast and furious it (to be able) to pick up more particles from the hillsides.

3. The river will deposit its sediments as it (to empty) into the estuary.

4. While sediments (to be) deposited they will form a definite layer.

5. If we (to look) at the layers they will show distinct examples of sedimentation.

6. When water containing dissolved substances (to evaporate) sediments also will be formed.

7. If the organisms (to be) bony or (to have) shells they will be preserved as fossils.

8. If we (to want) to date some particular rock layers we’ll use these fossils.

Lesson 9

Transport of sediments

Over millions and millions of years rocks are constantly formed and destroyed by enormous, but often slow acting forces. Rock fragments are weathered from the highest mountains often due to the expansion of water as it freezes. These fragments are then transported by either falling down rock faces or by fast moving streams. Either way it’s gravity that causes the movement! As the fragments are moved, they get bounced off other rocks and their shape becomes more rounded. The larger fragments only get carried by the faster flowing streams and so soon drop to the bottom. Small grains can however reach estuaries and even make it to the open sea where they fall to the bottom as sediment to begin the process of forming new sedimentary rock which may contain fossils. These may get forced to the surface again as the earth's crust moves and land masses collide together. Mount Everest was once at the bottom of a shallow sea and fossils can be found at the top!

Remember the words:

constantly – постійно to destroy – знищувати, руйнувати

enormous -- величезний to act – діяти

force – сила, to force -- змушувати weathering – вивітрювання

due to – завдяки, через expansion – розширення

either way – у будь-якому випадку either…or… – або… або…

to cause – спричиняти, змушувати movement – рух

to drop – падати bottom – дно, низ; top – верхівка

however – проте, однак to reach – досягати

make it to the open sea – потрапити у відкрите море

to collide – стикатися, зіштовхуватися shallow – мілкий, мілководний

to determine – визначати, встановлювати

Answer the questions:

1. Which process breaks off small fragments of rock? 2. Which force causes these rocks to move? 3. Explain why the size of a fragment of rock determines where it ends up? 4. How does the distance travelled by a fragment affect its shape? 5.What could happen to Mount Everest over the next few million years?