Binny Crag in West Lothian is of compact greenstone, about half a mile in length, and from twenty to one hundred and forty feet in breadth. It extends south and north, and has a small ravine on its west side, above which the highest part of the crag rises about two hundred feet. Three phenomena connected with this crag are worthy of observation. 1. It has the character of a trap vein which has ruptured the strata in a fluid state. The dip of the sedimentary rocks on its west side is to west-south-west, on the east side to the east, and in both cases at a pretty high angle. We have here, therefore, evidence of the strata having been ruptured, and a fissure formed; and we have the trap, the rupturing agent, placed on the fissure, and occupying the anticlinal line, or axis of the upheaving movement. According to the received hypothesis respecting the origin of trap, we might expect this appearance to be common, and yet it is rather rare.