380 



GEOLOGY OF THE SECOND DISTRICT. 



which have happened to this rock, and as they are so common to this region, it is proper to 

 describe them in tliis place. To illustrate clearly the points I wish, I refer the reader to 

 fig. 92. The sandstone is, as I remarked before, but slightly disturbed, and it usually deviates 



a, (I, Sandstone. 



b, Marsh, or low grounds. 



only slightly from a horizontal position ; but notwithstanding, we find it broken as represented 

 in the cut, and the fractured edges present an appearance like a wall of mason work, extend- 

 ing sometimes several miles in a direct course. Usually at some distance east or west of one 

 of these fractures, another wall runs parallel, or nearly so, and the space between the walls 

 varies from a few rods to half a mile. Now it is probable that in all instances of this nature, 

 the sandstone was continuous ; and that by the operation of some cause or causes, the rock 

 occupying the intervening space has been destroyed. The ground between such masses is 

 always low and swampy, and indeed is often a deep marsh. 



Another fact which is connected with the discovery of the cause of this state of the rocks, 

 is the rounding of the broken edges of the strata as represented in the cut, bearing also the 

 striae which are common on the flat surface of rocks over which drift has been transported. 

 Connected also with the above facts is another, viz. the direction of the strata coincides with 

 that of the stria? upon their surface, which is north and south, or northeast and southwest. 

 These phenomena all stand apparently connected together ; but the particular inferences which 

 may be drawn from them, I leave for others after having stated the facts. 



Whether these fractures belong to the same class of phenomena which I have already 

 described under the geology of Clinton county, some of which are called gulfs ox fissures, I 

 am not able to decide. In most if not all of the latter, rivers or creeks flow through them, 

 and the fractured edges, I believe, are not rounded. The difi'erence which may possibly 

 exist is in their ages ; those of Clinton being more recent, and like the gorges of Loraine, of 

 which mention has been made, they belong to the later changes, or those produced by causes 

 now in operation. 



Calciferous Sandrock. 



The Calciferous sandrock, though well developed in Jefferson county, is too much con- 

 cealed beneath the birdseye limestone, to enable me to speak at much length of its charac- 

 ters. But this has become unimportant, since I have already given a full description of this 

 rock. It occurs in place four miles south of Theresa falls, on the Watertown road. From 

 this place it continues three miles, but most of the distance it is concealed beneath the soil. 



