Mapping surface rocks is the first stage in modern oil
exploration. By studying the rocks on the surface,
geologists can guess at the structure of the rocks
beneath the surface. Another method that helps them
do this is to use an instrument called a gravimeter. This
measures the slight differences in the gravitational
force at different points on the surface of the Earth. The
denser rocks have a greater gravitational attraction
than the lighter rocks in the surface layers. By taking
gravimeter readings at a number of places along the
surface, it is possible to "map" the density of the rocks
below, thus helping to find oil.
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Feb 20, 18 12:47 AM
Second conditional (type two) grammar exercise with answers -- Check your answers at the bottom of the worksheet.
Feb 20, 18 12:43 AM
Second conditional (type two) grammar exercise with answers 2 -- Check your answers at the bottom of the worksheet.
Feb 17, 18 05:06 AM
Printable and online grammar exercises-- How Much vs How Many worksheets with answers
Feb 17, 18 04:29 AM
Unless means except if. We use unless to make an exception to something we say. See details with examples and exercises.
Feb 14, 18 09:57 AM
If conditional type 1 (first conditional) grammar exercise with answers-- Check your answers at the bottom of the worksheet.
Feb 14, 18 03:36 AM
Uses of In Case, detailed rules explanations with examples and exercises for English learners and teachers
Feb 14, 18 03:32 AM
Uses of Wish Clauses, grammar rules with examples, exercises, and detailed explanations.
Feb 14, 18 03:26 AM
IF clauses / First, Second and Third Conditionals (Type 1, type 2, type 3) categories explained with details, examples and exercises
Feb 14, 18 03:22 AM
Third conditional if is used for unreal situations in the past. Type three conditional grammar, with examples and exercises
Feb 14, 18 03:21 AM
Second conditional IF also referred as Type 2 conditional is used for...See second conditional rules, examples and exercises