n of these various fragments, inconspicuous as
they are, considerable can be deduced in regard to the environment of
the Weverton sandstone.

The submergence of the Catoctin Belt was practically complete, because
the Weverton sandstone nowhere touches the crystalline rocks. Perhaps
it were better stated that submergence was complete in the basins in
which Weverton sandstone now appears. Beyond these basins, however, it
is questionable if the submergence was complete, because in the
Weverton sandstone itself are numerous fragments which could have been
derived only from the granite masses. These fragments consist of blue
quartz, white quartz, and feldspar. The blue quartz fragments are
confined almost exclusively to the outcrops of the Weverton sandstone
in the Blue Ridge south of the Potomac, and are rarely found on
Catoctin.

The general grouping of the Loudoun formation into two classes of
deposit (1), the fine slates associated with the Weverton sandstone,
and (2), the course sandstones occurring in deep synclines with no
Weverton, raises the question of the unity of that formation. The
evidence on this point is manifold and apparently conclusive. The
general composition of the two is the same--i. e., beds of
feldspathic, siliceous material derived from crystalline rocks. They
are similarly metamorphosed in different localities. The upper parts
of the thicker series are slates identical in appearance with the
slates under the Weverton, which presumably represent the upper
Loudoun.

A marked change in the thickness of the Weverton sandstone occurs
along Catoctin Mountain, the formation diminishing from 1,000 to 200
feet in a few miles. This plainly indicates shore conditions, and the
nature of the accompanying change of constituent material locates the
direction of the shore. This change is a decrease of the feldspar
amounting to elimination at the Potomac. As the feldspar, which is
granular at the shore, is soon reduced to fine clay and washed away,
the direction of its disappearance is the direction of deep water.
Thus the constitution and thickness of the Weverton sandstone unite in
showing the existence of land not far northeast of Catoctin Mountain
during Weverton deposition.

Aside from this marked change in thickness, none of unusual extent
appears in the Weverton sandstone over the remainder of the Catoctin
Belt. While this is partly due to lack of complete sections, yet such
as are complete show a subst