268 GEOLOGY OF THE THIRD DISTRICT. 



Rising and going west from the primary which skirts Black riyer, the first range of rock is 

 the Black river limestone, forming a terrace coextensive with the county. It is its most 

 valuable rock for building, and for Ume, of which there are two kinds, the common and the 

 water-Ume. The upper layers of the terrace arc those which are intermediate to tlie Trenton 

 and the Birdseye limestone ; those below belong to the latter rock, and are the most valuable 

 for building, and burning for Ume, being more solid and pure. The part used for water-lime is 

 under the layers which are usually quarried, and where seen, was a yellowish color, and some- 

 what dull as to reflection of light. It was noticed only at the following localities : First, 

 near the mouth of Sugar river, at the quarries ; then to the east of CoUinsville ; and near 

 Lowville. It is no doubt coextensive with the cliff or terrace. The test of a water-lime, for 

 all practical purposes, is very simple. When the stone is calcined or burnt, it must not slake ; 

 and when ground and made into mortar, it must set and harden under water. It may be well 

 to remark, that generally less heat is required to bum this kind of limestone for the purpose 

 required, than to make ordinary lime. 



The Trenton limestone is the next rock in succession, rising upon the Black river limestone, 

 and showing a thickness of three hundred feet at its north end, but appearing to be less at its 

 south end. Its greatest known thickness is in this county. It ranges like the lower limestone 

 along the river, curving north, exposing a surface from two to four miles broad ; in some 

 parts rising rapidly from the lower terrace, in others by a gentle slope. From its great thick- 

 ness, it exhibits many fine water-falls yet unknov(m to fame, the greatest of which is near 

 Copenhagen ; and another is on Deer river, falling two hundred and seventy feet perpendicular 

 depth from towards the upper part of the rock. 



The Trenton limestone underlies the villages of CoUinsville, Martinsburgh, Lowville, Den- 

 mark and Copenhagen. It varies considerably in quality : in some places, greyish and crystal- 

 Une ; in others, more generally dark-colored, the separations of shale thick, and the limestone 

 frequently assuming an accretionary character from admixture of shale. It is a metalliferous 

 rock, galena having been found in it at three places, but not in profitable quantity as yet. The 

 first place where seen going north, is near Ives' mill, on the road from Shelden's to CoUinsville, 

 some particles being found in the quarry at the creek ; but it is more abundant at Lowville, 

 associated with other ores which were worked as silver. It is in considerable quantity at 

 Martinsburgh, but in veins too narrow to be worked with advantage under the existing state 

 of things. The rock appears near the surface at the highest point to the northwest of the 

 village. The veins are very numerous, and occupy the vertical east and west joints of the 

 rock ; continuous as to direction, both vertically and according to their east and west points, 

 but often interrupted for want of continuity in the joints. The ore is accompanied by blende, 

 and by what appears to be calamine, in which the galena often presents a beautiful feathery 

 form of crystallization. The stony materials are white crystalline carbonate of lime. The 

 joints are from zero to eight or more inches in diameter, ranging in parallels but a few feet 

 from each other ; their character is unknovni beyond a few feet from the surface, the greatest 

 depth attained being but fifty feet, and the thickness of the rock at that place, as previously 

 mentioned, being about five times that depth. 



