Transportation of fragments
If there is fast flowing water passing by the fallen rock fragments then some of these fragments (maybe not the huge boulders!) will be swept along by the water current. This can do two things:
It can move them, sometimes huge distances.
It can change their shape, as they bounce off other large particles.
Many particles become slightly smaller and more rounded in shape as they move down the river bed.
Larger grains are not carried as far as smaller grains since it takes more energy to
move them. As the river flows quickly down the mountain side it will carry a range of particle sizes, but as it levels out and travels more slowly, the larger grains are deposited as sediment.
This means that particles of a similar size are deposited at the same time, and in the same place. These form sediments and often show a clear distinction between different kinds of particles.
Remember the words:
to flow – текти, литися huge – величезний
to sweep – зносити, змивати current – течія
to bounce – підстрибувати, відскакувати river bed – дно річки, річище
to carry – нести, переносити range – ряд
to level out – нівелювати, вирівнювати deposit – відклад, поклад, родовище
similar – подібний, схожий same – той самий, такий самий
clear – ясний, чіткий, зрозумілий distinction – різниця, відмінність
Answer the questions:
On what condition will rock fragments be swept along?
What will they be swept by?
Why can rock fragments move, sometimes huge distances?
Why do rock fragments change their shape?
How do rock particles change their shape?
Do larger and smaller grains travel the same distance? Why?
What happens to larger grains when the river levels out?
How are sediments formed?
Lesson 8 Grammar: Future actions in when-, if- clauses 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:
When do rivers become fast and furious?
What can rivers do when heavy rains fall?
What does the river do when it empties into estuary?
What do the sediments form?
What is the other way by which sediments can be formed?
What do the dissolved substances form after evaporation of water?
What can be trapped in sediments?
Which organisms can be preserved as fossils?
How can fossils be used?
Exercise1. Use the correct tense forms of the verbs. All sentences refer to the future.
The river will become fast and furious if a heavy rain (to fall).
When the river becomes fast and furious it (to be able) to pick up more particles from the hillsides.
The river will deposit its sediments as it (to empty) into the estuary.
While sediments (to be) deposited they will form a definite layer.
If we (to look) at the layers they will show distinct examples of sedimentation.
When water containing dissolved substances (to evaporate) sediments also will be formed.
If the organisms (to be) bony or (to have) shells they will be preserved as fossils.
If we (to want) to date some particular rock layers we’ll use these fossils.