The igneous rocks will be described under the various groups of Granitic, Trappean, and Volcanic.

If there be any difference of date, it would seem that the fine-grained granite must be newer than the trappean rocks.

In its course it affords a good exemplification of the passage from the trappean into the plutonic, or highly crystalline texture.

Such masses are termed trappean agglomerate and trappean breccia.