ne white marble are seen; with rare exceptions also pebbles of
Catoctin schist and quartz occur. They are embedded in a red
calcareous matrix, sometimes with a slight admixture of sand. As a
rule the entire mass is calcareous.

The conglomerate occurs, as has been said, in lenses or wedges in the
sandstone ranging from 1 foot to 500 feet in thickness, or possibly
even greater. They disappear through complete replacement by sandstone
at the same horizon. The wedge may thin out to a feather edge or may
be bodily replaced upon its strike by sandstone; one method is perhaps
as common as the other. The arrangement of the wedges is very
instructive indeed. The general strike of the Newark rocks is a little
to the west of north, while the strike of the Catoctin Belt is a
little to the east of north. The two series, therefore, if extended,
would cross each other at an angle of 20 to 30 degrees. The
conglomerate wedges are collected along the west side of the Newark
Belt and in contact usually with the Weverton sandstone. The thick
ends of the wedges along the line of contact usually touch each other.
Going south by east the proportion of the sandstone increases with
rapid extermination of the conglomerate. The thin ends of the wedges,
therefore, resemble a series of spines projecting outward from the
Catoctin Belt.

The result of weathering upon the conglomerate is a very uneven and
rugged series of outcrops projecting above the rolling surface of the
soil.

The ledges show little definite stratification and very little dip.
The topography of the conglomerate is inconspicuous and consists of a
slightly rolling valley without particular features. It approaches
nearer to the level of the present drainage than any other formation,
and decay by solution has gone on to a very considerable extent. Where
the draining streams have approached their baselevel, scarcely an
outcrop of conglomerate is seen. Where the areas of conglomerate lie
near faster falling streams, the irregular masses of unweathered rocks
appear.

When but slightly weathered the conglomerate forms an effective
decorative stone and has been extensively used as a marble with the
name "Potomac marble," from the quarries on the Potomac east of Point
of Rocks, Maryland. While it is in no sense a marble, yet the
different reds and browns produced by unequal weathering of the
limestone pebbles have a very beautiful effect.

The thickness of the Newark formation is mo