Topograpliical Features of the JSFew Haveii region. 59 



South of the Hanging Hills of Meriden .an elevation commences which 

 stretches southward to Mt. Carmel, showing that the ice was arch- 

 ed up by the Meriden mountains, and the arch continued to Mt. Car- 

 mel. And here, as just observed, it was thrown anew into a high 

 arch for the ridging and ploughing southward, in the course of which 

 the Quinnipiac ridge was formed ; then it was raised by Whitney 

 Peak again, and its continuation East Rock; and finally it died 

 out as it left the region of Cedar Hill south of the East Rock range. 



Besides the large ridges and excavations made by the glacier, the 

 ledges over the hills are often approximately north-and-south in course, 

 and were probably a result of glacier ploughing. The chlorite schist 

 of the Woodbridge plateau is easily torn up in consequence of its 

 slaty structure and its joints or lines of fracture, and also readily 

 reduced to fragments by the freezing of water or growing of veg- 

 etation in the crevices. A large trap dike, intersecting this rock 

 on the Woodbridge heights west of Westville, often stands up above 

 the schist, as a prominent ridge, which sometimes has on one side or 

 the other a bare precipice of forty feet. But much of this wear is 

 undoubtedly the work of subsequent centuries. 



Without adducing other cases, it appears safe to conclude that 

 over the region of the Connecticut valley the principal part of the 

 coarse gouging out of the plains, and shaping of the mountains and 

 valleys, were performed by glaciers and by the streams that were in 

 action during the progressing and declining Glacial era. The same 

 agents also carried southward the earth, sand and gravel that were 

 afterward to be deposited by the ice, and worked over by the rivers, 

 or, near the sea-shore by the rivers, tidal currents and waves, into ter- 

 raced " alluvial " plains, or stratified drift foimations. 



Scratches having the course S. 33° W. — A wide variation from the 

 usual course of the glacier scratches (South, to S. 12° W.) occurs over 

 the chlorite rock along the Milford turnpike half a mile to a mUe 

 west of Allingtown. The place is about two and a half miles 

 south of West Rock, and one and a half miles south of the line of 

 East Rock. The course (true) of the scratches is quite uniformly S. 

 33° W., or full 20° west of the usual direction ; and they are so deep 

 and numerous and so completely free from crossings by scratches in 

 any other direction, that S. 33° W. must be viewed as the course of 

 the under surface of the glacier over this part of the western margin 

 of the New Haven region. The scratches are seen at the top of the 

 first ascent on the turnpike, about 1 30 feet above the sea, (or 90 

 above the level of the New Haven plain), and at many other points 



