Anticline and Syncline
1. regarding
2. in most cases
3. because
4. specifically
5. furthermore
6. respectively
7. upward
8. downward
9. consequently
10.
sometimes
a) towards a higher place, point,
or level
b) as a result
c) distinctly , clearly
d) in the same order as the items
that you have just mentioned
e) as regards the greater part or
number
f) towards a lower place or level
g) for the reason that; since
h) in respect of; concerning
i) occasionally, rather than all of
the time
j) moreover
Anticline and Syncline, in geology, terms used to describe folded rock
layers where the relative ages of the layers are known. (1)…...., anticlines
are folds in which the oldest rocks are in the core, or center of the fold,
while synclines have the youngest rocks in their cores. (2)…...., anticlines
are arch-shaped while synclines are trough-shaped. In unusual cases
where older rock layers lie on top of younger layers, anticlines are troughshaped and synclines are arch-shaped. If the relative ages of the rock
layers are unknown, then the terms antiform and synform describe arch
and trough shapes (3)…..... The size of folds, measured from the crest of
one arch to the crest of the next arch, can range from less than a meter
(about 3 ft) to greater than 10 km (about 6 mi).
Anticlines and synclines form when rock layers are compressed, just as a
carpet folds when its sides are pushed together along a floor. When rocks
are compressed, they can either bend or fracture. When rocks bend they
create folds, and when they fracture they can produce faults. (4)…...., many
folds are associated with faults.
Anticlines and synclines are useful to geologists for a variety of reasons.
They give information (5)….... geologic history. By determining the age of a
fold, geologists can determine when the earth’s crust in a given area was
compressed. (6)…...., the orientation of the fold provides information
regarding the direction of forces within the crust.
Geologists who explore for oil and gas seek out anticlines (7)….... the
arches form natural traps for these hydrocarbons. Oil and gas are less
dense than water and tend to migrate (8)..….. through permeable rock
(rock that allows movement of fluids). If the rock is folded into an anticline
and capped by an overlying impermeable rock, then oil and gas will migrate
up the slope of the fold to the crest and accumulate there.
Hydrologists looking for an underground water supply, or aquifer, seek out
synclines because synclines can form natural traps for water. Water tends
to migrate (9)….... through permeable rock until it reaches impermeable
rock or reaches a level, called the water table, where groundwater fills all of
the available spaces below it. If permeable rock is folded into a syncline
and impermeable rock lies at the bottom of the syncline, then water will
accumulate at the bottom of the syncline. (10)….... the level of the
impermeable rock at the bottom of a syncline lies above the level of the
water table. When this occurs, water accumulated at the base of the
syncline will be perched above the water table. Such accumulations of
water are called perched aquifers. Perched aquifers are valuable because
their relatively shallow depths make the cost of drilling wells far less
expensive than drilling wells down to the water table.
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