NATURAL HISTORY. 



45 



GiLiMPLAIN GROUP OF ROCKS. 



RED SANDROCK. 



TUE OVKN. 



Point. AVe are aware that it has been gen- 

 erally called Sharpshins, but we think that 

 it is quite time that vulgar name was dis- 

 carded. 



Towards the northern paii of this uplift 

 there commences a bed of dove-colored 

 limestone, between the shale and the sand- 

 rock, which appears with increasing thick- 

 ness at Mallet's Head and St. Albans Bay; 

 and at Swanton is quarried for marble. 

 From Swanton it continues northward into 

 Canada. 



One of these uplifts, that of Snake Moun- 

 tain, affords a fine exhibition of all the 

 members of the Chaniplain Group of rocks, 

 which we have been describing, as may be 

 seen by the section below, which is copied 

 from Prof. Adams' Second Annual Report 

 on the Geology of Vermont, p. ]fi?,. 



/ > 





Hi 



a. Red Sandrock, forming tlie summit of the 



mountain, Avith an easterly dip of 20 . 



b. Debris from the Red Sandrock. 



r. Hudson River Shales, considerably cov- 

 ered with drift and debris. 



d. TJtica Slate. 



e. Trenton Limestone. 



_/'. Isle la Motte Limestone. 

 "•. Calciferous Sandstone. 

 /(. Clay. 



The rocks, which constitute the Red 

 Sandrock series, differ vci-y much in color, 

 and in composition, or lithological charac- 

 ter. The lower strata are, in many places, 

 considerably calcareous, and thick-bedded, 

 with the planes of stratification so much 

 obliterated, as to give them the appearance 

 of an igneous, or unstratified rock. The 

 color of this portion is often gray, or varie- 

 gated with different sliades of brownisli red 

 and yellowish white ; and parts of it are 

 sufficiently calcareous to admit of being 

 polished, and make a very compact and 

 beautiful variegated marble. The best 

 specimens of this have been found in boul- 

 ders in connexion with the drift. 



The middle portion of this sei'ies is almost 

 entirely siliceous, and, through a great 

 part of its extent from south to north, is of 

 a dark reddish brown color ; and it is the 

 color of this portion which has given the 

 name of Red Sandrock to the series. But 

 in some places, this middle portion is nearly 

 destitute of coloring matter, appearing as 

 a light gray stratified quartz rock. In some 

 places it is so purely siliceous as to be suit- 

 able for the manufactui-e of glass. Cases 

 also occur, where a sti-atum of pure white 

 quartz intervenes between strata which 

 



are highly colored. There is an example of 

 tliis in Vv'illard's quarry, in Burlington. 



The colored strata of this sandrock fur- 

 nisli a very durable and beautiful stone for 

 foundations and underpinnings of build- 

 ings, and, though somewhat refractory and 

 difficult to work, has been very much used 

 for tliat purpose. The foundations of the 

 greater p-M't of the buildings in Burlington, 

 are of this material. 



i'rom the middle portion of the Red 

 Sandrock series, the strata become more 

 and more calcareous, in proceeding upward 

 and eastward, till thej', at length, become 

 in many places a very pure limestone. This 

 limestone is, generally, of a Ijluish color; 

 but in some places, particularly in the east- 

 ern part of Shelbui'ue, its color is pure 

 wliite. Portions of this limestone make 

 the vciy best of quicklime, which is largely 

 manufactured from it, not only for use in 

 the neighborhood, but for transportation 

 into the interior of the state, and to places 

 where no good limestone exists*. At Pen- 

 uiman's quarry and kilns, which are by 

 the side of the railroad above Winooski 

 Falls, Messrs. Penniman & Catlin manu- 

 factured, in 1852, about 67,000 bushels of 

 quicklime, and others, in the neighborhood, 

 manufactured about 40,000 bushels, ma- 

 king over 100,000 bushels, the principal 

 part of which was sent by railroad into the 

 central and eastern parts of the state, and 

 to other parts of New England. 



Some portions of the Red Sandrock series 

 arc very regularly and handsomely stratifi- 

 ed, but other portions are much disturbed 

 and broken, or bent and folded. One of 

 tlie most interesting plications in this rock, 

 which have been noticed, is in Monkton. 

 The south end of this plication is repre- 

 senteii in the figure below. 



The white spaces 

 between the curv- 

 ed lines represent 

 the edges of the 

 strata. These are 

 \ all of the ordinary 

 \* sandstone. The 

 ^ Oven. '^ broad dark stra- 



tum, c c, is argillaceous slate, having the 

 laminnc nearly perpendicular to the plane 

 of deposit. The upper portion of this, 

 which is left wholly dark, has been remov- 

 ed, forming the cavity called tJie Oven. 



■ The ccood qualities of the quicklime manufactured 

 from tliis stone is not only attested by those, who 

 liave used it iu tliis country, but lias been fully ac- 

 knowledcred, by competent judges, a))road. Iu 1851, 

 U. H. Penniman, Esq., sent out a cask of his lime 

 for exhil>ition at the World's Fair, in London. This 

 lime was examined, liy a Jury, appointed for that 

 purpose, under the royal commission, and this jury 

 awarded him a Prize Medal and Certificate, as tes- 

 timonials of its superior excellence, placing it in the 

 first rank in competition with, the world. 



