Mean sediment thickness, volume of detntal quartz, and grain size distribution of dctrital quartz have been calculated for the total sediment mass of the earth's crust. Sedimentologic and petrographic data were used rather than geochemical data. Results are in good agreement with the earlier estimates based on geochemical arguments. Mean sediment thickness is computed to be 2690 feet and represents the erosion of 7640 feet of crystalline rocks.
The percent of detrital quartz in the sediment mass is estimated to be 21.0 percent. The detntal quartz has a mean grain size of 4.0ϕ its frequency-distribution is log-normal with standard deviation of 2.5ϕ. As earlier work has indicated the mean size of quartz from newly disintegrated crystalline rocks to be 0.67 mm, the mean size of 0.06 mm determined for the earth's detrital quartz represents a size decrease of 90 percent by sedimentary processes.