Page 37 - History of Rockingham Co
P. 37
A HISTORY OF
The Shenandoah Hmestone varies in color from a grey to
dove color and blue. It contains frequent cherty beds, the
weathering of which gives rise to the ridges and gravelly hills
common in the county. Shaley beds also occur within the
hmestone of varying thickness. The most prominent of these
are the Buena Vista shales of Cambrian age, which are easily
recognized by their reddish color. In composition the rock
varies from an almost pure limestone to dolomite, in which
the lime is replaced largely by magnesia. The rock also
shows widely varying percentages of clayey material and
siHca. The Chambersburg and Stones River formations and
the associated Trenton shales afford splendid material for the
manufacture of Portland cement.
In the upper part of the Shenandoah limestone shaley
beds appear, which increase in frequency and thickness till
the formation entirely gives way to the Martinsburg shale.
This shale formation occupies a prominent synclinal trough
extending entirely across the county. This syncline is known
as the Massanutten syncline, since its position is partly oc-
cupied by the mountain of the same name. The syncline is
very persistent, and extends far beyond the limits of the
mountain both to the northeast and southwest. There are
also other minor areas of the shale formation which may be
seen on the accompanying map. The thickness of the forma-
tion is about 2000 feet. The fine blue slate lands of the county
are underlain by the lower beds of this formation. The
weathering of the shale gives rise to the characteristic rounded
hills with oval crests, often very similar in form to the drum-
lins of glacial origin in the northern part of the United
States. The contact between the shale and limestone can
readily be detected by the abrupt change in the topography.
The Martinsburg shale is succeeded by the Massanutten
sandstone, so called from its occurrence in the mountain by
that name. It is to the resistant character of this rock that
the Massanutten mountain owes its existence. The thickness
of the sandstone is about 500 feet. It varies from a reddish
sandy shale to a coarse conglomerate and light grey massive
The Shenandoah Hmestone varies in color from a grey to
dove color and blue. It contains frequent cherty beds, the
weathering of which gives rise to the ridges and gravelly hills
common in the county. Shaley beds also occur within the
hmestone of varying thickness. The most prominent of these
are the Buena Vista shales of Cambrian age, which are easily
recognized by their reddish color. In composition the rock
varies from an almost pure limestone to dolomite, in which
the lime is replaced largely by magnesia. The rock also
shows widely varying percentages of clayey material and
siHca. The Chambersburg and Stones River formations and
the associated Trenton shales afford splendid material for the
manufacture of Portland cement.
In the upper part of the Shenandoah limestone shaley
beds appear, which increase in frequency and thickness till
the formation entirely gives way to the Martinsburg shale.
This shale formation occupies a prominent synclinal trough
extending entirely across the county. This syncline is known
as the Massanutten syncline, since its position is partly oc-
cupied by the mountain of the same name. The syncline is
very persistent, and extends far beyond the limits of the
mountain both to the northeast and southwest. There are
also other minor areas of the shale formation which may be
seen on the accompanying map. The thickness of the forma-
tion is about 2000 feet. The fine blue slate lands of the county
are underlain by the lower beds of this formation. The
weathering of the shale gives rise to the characteristic rounded
hills with oval crests, often very similar in form to the drum-
lins of glacial origin in the northern part of the United
States. The contact between the shale and limestone can
readily be detected by the abrupt change in the topography.
The Martinsburg shale is succeeded by the Massanutten
sandstone, so called from its occurrence in the mountain by
that name. It is to the resistant character of this rock that
the Massanutten mountain owes its existence. The thickness
of the sandstone is about 500 feet. It varies from a reddish
sandy shale to a coarse conglomerate and light grey massive
