Uphole and low velocity layer (LVL) surveys

Abstract

Apart from the rare instances where, over large areas of the surface of the ground, consolidated rock is exposed, the material that appears at the surface is made up of the remains of older rock that has been subjected to some form of decomposition, given the general description of weathering. This material is said to have been weathered. It could have been deposited as a result of the movement of fine particles by the action of the wind, such as is the case with loess and sand dunes. It could have been deposited as a result of the action of rivers, as in alluvial plains, or of glaciers. On the other hand, it may be composed of the remains of previously consolidated rock whose nature has been changed by the action of ground-water, either physically or chemically, or some other means.