114 The Limestones, and Lime. [March, 



The rock is often an excellent building stone, and has been em- 

 ployed largely in the construction of canal locks and other struc- 

 tures which require a durable material. A gray variety, which 

 is quite uniformly crystalline, resembles granite at a distance. 

 The cathedral of Montreal is constructed of this rock. 



Distribution of the Rock in JYew-York. — The calciferous sand- 

 stone is but imperfectly developed in the valley of the Hudson. 

 It appears occasionally as a fossiliferous band, resting upon the 

 Taconic slate. It may or may not have formed a continuous 

 bed. It appears upon the knobs or highest of the hills, as at 

 Greenbush and Troy. It is quite common to meet with it when 

 it has assumed the form and condition of a breccia. Undoubtedly 

 some of these beds are merely accietionary; others, however, are 

 real conglomerates, inasmuch as the pebbles are distinctly rounded 

 and frequently weather out, and leave a smooth round cavity in 

 the mass. 



This rock is prolonged from the Hudson into the Champlain 

 valley, and increases in thickness, and is visibly more continuous 

 here than in the Hudson valley. This rock, however, is mainly 

 important in New-York, in the immediate region of the northern 

 highlands, which it surrounds as a band, and an outcropping 

 rock above the Potsdam sandstone; and it dips quite regularly 

 from this great primary mass. 



The most remarkable localities are in the Mohawk valley, 

 where it foims quite a conspicuous rock at the Noses and Little- 

 Falls. The most perfect exhibition of this rock, however, is at 

 Chazy, where it is highly fossiliferous. It is here that it forms 

 such a contrast with the limestones of the Taconic system; and it 

 is here that we have an instructive series of fossils belonging to 

 the earliest of the brachiopods and crustaceans, which orders 

 have survived all the geological changes, and have come down to 

 us as it were in their earliest forms. We have said survived, be- 

 cause it is the common expression or phrase. It carries, however, 

 an erroneous view, and needs correction. The survivors of these 

 orders are no more the lineal descendants of these ancient fami- 

 lies, than are the present quachupeds. The true representation 

 lies in Ihe fact that these orders have been continued by creation, 

 and not l}y generation; and hence they cannot be said to have 

 survi\e(l llie changes which have taken place since the deposition 

 of this rock, inasmuch too as it cannot be shown that they have been 

 exposed or subjected to those changes in that mode and manner 

 which would tend to exterminate them. The scheme of creation 

 being determined upon by the ('reator, which in itself was adapt- 

 ed to the chemical and physical conditions of the globe, has been 

 continued and acted upon during the nnmense lapse of time which 

 ha.s intervened between the era ol' protozoic life and the present. 



