Acoustic radiometer, used to measure the acoustic power of a sound beam in water. The vane is suspended from a pendulum whose rotation is opposed by gravity. Deflection Δ x of the vane is proportional to the force on the vane.
Exposure of glacial till at the Black Rocks near Llandudno, Wales. Heterogeneous debris, ranging in size from large boulders to fine powder, displays no sorting or stratification. (Photograph by K. F. Mather)
Relationship between compressional-wave seismic velocity, igneous rock type, silica content, and density. Seismic refraction profiles provide a measurement of compressional-wave velocity as a function of depth in the crust.
Average crustal columns for seven geologic provinces, showing variations in crustal thickness (light gray areas correspond to the mantle). Compressional-wave velocity, which has been divided into five ranges, is directly related to geologic…