262 THE COASTAL PLAIN OF NORTH CAROLINA.

more or less regularly disseminated clay content. At some places a
large percentage of the pebbles and cobbles in the gravel beds are
smoothly rounded, and this is especially true wherever there are con-
siderable accumulations of gravel. Where very thin coverings of the
deposits occur, however, resting directly upon the crystalline rocks a
considerable percentage of angular or slightly worn quartz is, asa rule,
intermixed with the well-worn material. ot

The materials of the Lafayette formation in most places present a
dull or soft yellowish or reddish appearance, due to the presence of
thin films of iron oxide coating the sand and clay particles. They differ
in this respect from the unweathered sands and clays of the Patuxent

formation which, as before stated, form the underlying strata over
part of the area, the latter being as a rule light in color, light drabs-

and grays prevailing. The Lafayette materials, however, are in