Unconformable
in geology, the term used when one series of beds is so placed over another that the superior beds repose more or less on the edges instead of on the planes of the inferior series. Thus on the borders of Wales and Shropshire the slaty beds of the Silurian system are curved or vertical, while those of the overlying carboniferous shale and limestone are horizontal. To produce unconformity, three series of events have generally occurred. First, the inferior beds, originally laid down horizontally, must at some subsequent time have been tilted up by a force, probably igneous, from beneath. Secondly, in most cases, the upturned ends