Dyke

Ma of igneous rock traversing sedimentary or other strata, often like a wall. Dykes are sometimes of great breadth, and as often exceedingly narrow. They cut the strata at all angles, and the rocks on each side frequently give evidence of the heated condition of the dyke at the time of its intrusion. The sides of volcanoes are usually intersected by dyke walls the materials of which were forced into them from the crater by hydrostatic pre ure.