TERTIARY SYSTEM. 



203 



tiot been examined very carefully, it is not at all improbable but tliat all may yet be found 

 in the range of latitude which these fossils themselves now occupy. We have reason to 

 expect this. 



Upon Lake Champlain, Port Kent is the best point for procuring these fossils. The 

 locality is about eighty rods south of the steamboat landing, in the clay bank, twenty-five 

 feet above the level of the lake. If the shells are immersed in a weak solution of glue, 

 the colors will revive and become permanent. 



For additional facts respecting this formation, see the Report of the Second district, in 

 which the fossils are figured. 



The Tertiary system, as already stated, extends into the valley of the Hudson. The 

 fact of its extension is sustained by its continuity with that in the valley or basin of the 

 Champlain. The character of the formation, in its southern prolongation, does not differ 

 essentially from that already given. It may be regarded as extending to New-York bay, 

 and probably westward into the valley of the Mohawk. Its full extent, however, can not 

 be clearly defined. Its composition is quite uniform, as will appear by the analysis of the 

 clay obtained at distant points. At Albany, this clay is an important material for making 

 brick. In the process of extending the bounds of the city, a mass from ten to twenty feet 

 thick has been removed, in order to bring the surface to a uniform grade. The banks 

 exposed by this operation often present many curious contortions, of an anomalous cha- 

 racter, and difficult to explain. A mass of ten feet thickness which has been exposed by 

 a vertical section, is highly contorted, while its base rests upon horizontal strata. An 

 illustration of this curious contortion is furnished in the following cut (fig. 33) . A portion 



Fig. 33. 



on the left, which is bent, rests on the undisturbed clay bed below : in the middle it is still 

 more contorted, and is a miniature representation of phenomena which are often witnessed 

 in slates and shales of the different formations, and usually explained by tlie action of some 

 uplifting force, accompanied by lateral pressure. This explanation is properly given in 

 many instances. These contortions of (he clay beds, however, seem to indicate the possi- 

 bility of their production by other causes ; for there will be found but few persons, who, 

 after examining the instances here specified, will advocate the doctrine that these clay 

 beds have been forced upward or wrintlcxl by lateral pressure, in the mode this force is 

 usually supposed to act. It appears, after a careful examination of the circumstaces at- 

 tending these irregularities, that they take place at points where the adjacent beds have 

 been removed : they are then left unsupported on one side ; and in consequence of this 



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