ESSEX COUNTY. 283 



TERTIARY OF ESSEX COUNTY. 



After having given a very full description of the tertiary of the northern district, it will be 

 needless to occupy time and space with repetitions of what has already been stated of this 

 deposition. I shall therefore only observe, that all the argillaceous depositions, excepting 

 those more than four hundred feet above Lake Champlain, belong to this formation. We find 

 it spreading out and occupying most of the surface adjacent to the lake, where the primary 

 rocks do not come down boldly, or terminate in high cliffs. It possesses the ordinary cha- 

 racters of clay, but is more calcareous than the plastic clays of Amboy. It differs in another 

 particular from some of the tertiary clays of an earlier period, as it never contains sulphuret of 

 iron, either in nodules or in fine disseminated particles. The foreign substances, either mineral 

 or vegetable, which I have observed in it, are extremely limited, as will be seen by the fol- 

 lowing statement : Lignite has been found in one instance ; the locality at which it may pro- 

 bably now be seen, is in a meadow belonging to Mr. Whallon of Essex. It is in small 

 pieces, being merely some of the common kinds of wood which have become carbonized by 

 the usual agents. From some portions of this tertiary, springs issue, highly charged with 

 epsom salts : the shore between the old fortress on Long point and Crown-Point village, fur- 

 nishes several. In a dry time, large surfaces of the clay are covered with a bitter saline efl3o- 

 rescence. Wells dug in this clay are invariably filled with hard water ; and if they are situated 

 in those beds which throw out a saline efflorescence, they are wholly useless, and are not even 

 fit to supply cattle with water, unless they happen to be filled with rain water. They may 

 sometimes be used as reservoirs, the contents of which will serve for ordinary purposes, when 

 well supplied with rain water. Clay stones, or small septaria, abound in many places : they 

 are of every variety of form ; and I may here remark, that wherever calcareous matter is 

 mixed with argillaceous, the former invariably separates, and forms these singular bodies. 

 Wherever they exist, it is an indication that the clay is unsuitable for bricks, inasmuch as it 

 contains too much lime, which, after the bricks are burned, will slake, and destroy their 

 texture. 



Two genera of molluscous animals are found tlu-oughout the entire length of Lake Cham- 

 plain ; they are, the Saxicava rugosa and Tellina groenlandica. The place most favorable 

 for observing this formation, is Port Kent. Several shells occur here, which are not to be 

 obtained at any other place upon the lake ; such as the Mytilus edulis (which has been 

 referred to under the name of Modiola), Balanus, and one or two others : the former is the 

 most common and perfect of the fossils at this locality. At this place, too, the whole forma- 

 tion exists — all the clays and sands, with the intermediate varieties. 



This lower mass of the clays forms a good brick ; and the upper, which appears to be 

 more calcareous, may undoubtedly be employed to give greater consistence to the sandy soils 

 in the vicinity. The sands of these beds are rarely sufficiently free from feldspar, augite, 

 iron, etc., to be employed for glass, and they answer merely for ilie ordinary kinds of mortar. 



Though this formation has been stated in general terms as occurring the whole length of 



