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Determining the depth of a body of water by an echo sounder or sounding line.
Measuring the depth of bedrock by driving a steel rod into the soil.
Any penetration of the natural environment for scientific observation.
Knocking on a mine roof to see whether it is sound or safe to work under.
Subsurface investigation by observing the penetration resistance of the subsurface material without drilling holes, by driving a rod into the ground or by using a penetrometer.
The measurement taken of all parameters in and of the upper atmosphere or of the sea.