126 CHAMPLAIN DIVISION. 



thiii-hrddcrl Lorainc shales : the thick-bedded superior masses are wanting, though at Rome 

 and its vicinity they are well developed, and appear even-grained and even-bedded, so 

 much so as to be employed in the manufacture of grindstones. 



This rock, at the Shawangunk range, is thick-bedded, and rises in mural escarpments 

 of from thirty to two himdred feet. The position is often horizontal, but not always so, 

 inasmuch as it is found dipping at a high angle to the southeast ; and in other places, par- 

 ticularly upon the west side, to the northwest at a variable angle. In New- York, this 

 rock extends from the New-Jersey line to Rosendale near Kingston, a distance of forty- 

 three miles. The range is narrow, direct, and of a very uniform height, similar in this 

 respect to the more southern ridges of Pennsylvania. The maximum thickness of the 

 Onieda conglomerate of this range, is estimated by Mr. Mather at five hundred feet. 



It is not well settled where this rock belongs, or in which of the two divisions it may 

 be placed with the least violence to the rules of classification — whether in the Ontario 

 division, or in the Champlain. This difficulty is created by the absence of fossils, ex- 

 cepting a few obscure casts of fucoidal stems. It may be regarded as an intercalated 

 rock ; as a landmark, indicating that a very important change has taken place, which 

 marks the termination of one era, or the commencement of another. If we regard it as 

 marking the termination of a period, it belongs to the Champlain division : if it is consi- 

 dered as the beginning of an era, it will belong to the Ontario division. Its importance as 

 a way-mark is unaflected by either view of the case. Being made up of rolled stones and 

 pebbles, it must have formed the shore of an ocean when it was consolidated ; after 

 which, it was elevated. Or, as some would regard it, it was formed as before stated of 

 stones rounded by attrition ; but they were brought together during a period of turmoil, 

 which affected very materially the existing races of animals. 



^ 10. General range and extent of the champlain division. 



If we separate clearly this lower division from the succeeding ones, we have mastered 

 the geology of New-York. Nature has done this, and there is scarcely a locality where 

 the rocks succeeding this division are so intermingled as to lead necessarily into error. 

 We turn our attention first to the Mohawk valley, for in this we find a definite southern 

 boundary. In this remark, however, we adopt what was the ancient boundary, rather 

 than what appears to be its present limits, especially of the eastern part of it. 



To obtain a point of departure, let the reader in imagination pass over the Schoharie 

 stage road from Albany, but stop sixteen miles west. This part of the route is over the 

 shales of the Hudson river, concealed mostly for the first ten or twelve miles by the 

 tertiary clays and sands. The last mile, however, he ascends the northern terminus of 

 the Helderberg range. The first part of the ascent is still Hudson river, and thus it con- 

 tinues until he has apparently reached the highest part of the mountain. A little to the 

 left of the road on the westerly route, less than half a mile, the limestones of the Helder- 



