.
AGE
Depth
(million
(km)
years)
sa
____________
_____________
—:::—_——:—”:————::—
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0.5
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3
_______
___:
135
… “_…
——
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1.5
—_—_—_———“
_
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sandstone
___:
E
_______—_—:—:—:—*—=
3
__
__
_
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______________.______
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_
_
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_{{—_—_—_
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_
sandstone
_____
225
+
+
+
+
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+
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+
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+
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sandston
270
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coal
3.0
figure 10 section through the North Sea floor
showing rocks bearing deposits of natural gas