410 
GEOLOGY OF THE FIRST DISTRICT. 
5. Calciferous Group. 
Synonims. Barnegate limestone, Newburgh limestone, Warwick limestone. Oolitic limestone, Fu- 
coidal layers. Slaty limestone, of the Geological Reports of New-York; Calciferous'sandrock 
and Transition sandrock of Eaton. No. 2 of the Pennsylvania Survey. 
This group of rocks is intermediate in composition, as it is in age, between the Trenton 
and Mohawk limestones on the one hand, and the Potsdam sandstone on the other. The 
rocks are calcareo-siliceous ; and sometimes one, sometimes the other predominates, and gives 
character to the rock. The water-lined laminae of deposition are very conspicuous in some 
of the strata of calciferous sandstone. 
The rocks of this group occupy a long narrow belt in the First geological district, extend¬ 
ing from the New-Jersey line, south of Warwick and Pochunk neck, by Newburgh, Marl¬ 
borough, Barnegate, Pleasant-valley, Pineplains, Ancram, Hillsdale, Canaan, Lebanon 
springs and Williamstown, into Vermont. There are numerous smaller patches where these 
rocks have been upheaved and exposed, that are not continuous for any considerable distance ; 
and a similar remark may be made in regard to the long belt of limestone above described. 
It is not absolutely continuous, but has been fractured across, and heaved out of place along 
faults transverse to the lines along which the principal disturbances have taken place. 
Barnegate Limestone. 
The first continuous range of limestone of much magnitude that is seen in Columbia and 
Dutchess counties, in passing from west to east, is that which crosses the Hudson at Barne¬ 
gate. It extends from Barnegate up Wappinger’s creek, by Pleasant-valley and Pineplains 
into Columbia county, and on the south it passes from Milton by Newburgh, down the great 
valley through New-Jersey into Pennsylvania. Wappinger’s creek forms the eastern boundary 
of this limestone range to near Attlebury. It crosses the valley of Pineplains under the great 
peat and marl marsh and Stessing pond. Mount Tom, at Copake flats, is a continuation of 
the same limestone. It varies in its characters from a sandy granular subcrystalline texture, 
to a perfect compact limestone, with a conchoidal fracture. This limestone is usually grey, 
granular, and subcrystalline, with grains of sand and minute quartz crystals disseminated. 
Small cavities lined with quartz crystals are common. 
It is said to contain fossil remains, but they must be very rare, as I have not been able to 
detect a trace of one.* It is sometimes distinctly stratified, and even slaty near its junction 
* Mr. Briggs, in making his section from Poughkeepsie in Dutchess county, to Canaan in Connecticut, discovered 
faint traces of shells in the limestone at a quarry a little south of Pleasant-valley, on the hank of Wappinger’s creek, but 
they were too imperfect for determination. “ They were situated between the slaty layers, which dip to the south-south¬ 
east at an angle of thirty-five to forty degrees. Mr. William Thorn, of this place (Pleasant-valley), informed me that 
he had often seen shells in the limerock, although they are rare,” (Mr. Briggs’s Geological Notes of New-York Survey, 
Vol. ii, p. 252.) 
