Introductory.—The phenomenon to be described in the following pages is that of the occurrence of sandstone—a rock composed of worn sand grains—as the filling of an extensive system of fissures in granite and under circumstances indicating that the sand was forced into the fissures under great pressure.
Region of Occurrence.—The sandstone masses in question occur in the Pikes peak region, in Colorado, and were discovered in the course of a geological survey of the district during the past summer of 1893.† The dikes observed are limited to a belt about ten miles long and one mile wide, with a trend north-northwest to south-southeast, the southern end of which is about five miles north of Pikes peak. This belt lies on the western side of the narrow Manitou park basin of sedimentary rocks, at a distance six to eight miles west from the border of the Great . . .