354 
GEOLOGY OF THE FIRST DISTRICT. 
The red shale and slate, No. 5 of the above section, may, perhaps, for economical pur¬ 
poses, be called sfred marl. It contains some lime, and there' are several thin bands of lime¬ 
stone. The whole of this stratum has the aspect and composition of the red marl rock of 
Rockland county (new red sandstone), but has a different geological position. 
The pyritous slaty limestone lying next above, is more or less argillaceous, and loaded 
with crystallized pyrites, which are continually decomposing and forming gypsum. The 
mineral thus formed coats the rocks in brilliant druses or flocky and acicular efflorescences. 
Epsom salts are also formed, if the taste is to be trusted ; and Mr. Robinson, the owner of 
the locality, says, that the saline matter sparkles or deflagrates slightly when thrown on red 
hot coals. This sparkling would indicate the presence of nitrate of lime. 
I advised Mr. Robinson to grind some of the pyritous limestone and red marl, as they are 
easily crushed; and when spread on the ground and exposed to the weather, both would give 
rise to the formation of gypsum, by the decomposition of the pyrites, and the combination of 
the sulphuric acid thus formed with the lime. He has since ground some of the rock, and 
made a trial of it as a substitute for gypsum, and has found that it answers the same pur¬ 
pose, promoting the growth of vegetation in a sensible degree. The slaty limestone is rich 
in pyrites, minute crystals of which are disseminated through its mass. 
At Schoharie, near the bridge over the creek, the stratum containing the pyrites is exposed, 
underlying the Helderbefg limestone series. This locality has been long known in conse¬ 
quence of the fine crystals, and groups of crystals, imbedded in the decomposed clayey green 
shale. 
Many places were observe^^sywhere the same crumbling green shale, interlaminated with 
limestone, and containing an abundance of pyrites, was underlying the Helderberg limestone 
series. The slate, or dark colored shale, which contains the fibrous sulphate of baryta, lies 
directly below the pyritous rock in Carlisle and Sharon in Schoharie county. 
The red rock, under various modifications of texture, is found on the northwest side of 
the Shawangunk mountains, and in the valley, in various places from near Rosendale to the 
New-Jersey line near Carpenter’s point. 
It is sometimes a red, and mottled red and green shale, ^ith thin bands of limestone and 
balls of pyrites, like that described above at High falls ; at others, it is a gritty shale or 
slate, or a chocolate or red colored grit rock, sometimes soft like freestone ; at others a hard 
sonorous quartz rock. Passing from Wurtsboro’ to Bloomingburgh, “ it is crossed about one 
fourth of the distance up the mountain on its western side. It may also be seen in many 
places between that locality and the New-Jersey line.” “ In many places, hand specimens 
could not be distinguished from the New-Jersey sandstone.” 
On the road between the Shawangunk lead mine and the smelting house, the red rock is 
seen as a crumbling slaty sandstone of a chocolate color. 
At the High falls of the Rondout in Marbletown, Ulster county, the red rock is a shale 
and fine slaty grit, spotted with green, and interlaminated with thin bands of limestone. It 
is there covered by the Water-lime series of the Helderberg division. 
