654 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



An inspection of this Westfield-Southwick plain as represented on the 

 map will, I think, convince one that it was constructed by a broad, very 

 shallow body of water, often broken into separate threads meandering across 

 the plain, which were separated from one another by long intervening- bars 

 and spits, bounded by construction scarps, at times quite steep and fluted 

 on the convex side of the curving channels, but often of long and easy slope. 



THE GKEATER ELEVATION OF THE TEREACES IN THE WESTFIELD THAN IN THE 

 SPRINGFIELD LAKE. POSSIBLE WESTERN ELEVATION. 



Professor Dana has noted that the highest normal terraces in the west- 

 ern valley are 50 feet higher than in the eastern. Mr. J. S Diller has 

 discussed the matter in an interesting article which was published in the 

 Westfield Times and News Letter, September 19, 1877, and which is here 

 reproduced : 



THE GEOLOGY OF 'WESTFIELD AND VICINITY. 



By J. S. Diller. 



Professor Dana has shown that at Tariifville, Connecticut, where the Farming- 

 ton Kiver flows through the Divide range, the terraces upon the west side of the 

 range are about 50 feet higher than those upon the east side. At the Westfield 

 gap, through the Divide range, the upper terrace on the west side of the range is 2Qii 

 feet above sea level, but on the east side the highest terrace is 50 feet lower. It has 

 been shown by Professor Dana that during the Champlain period the highest flood 

 level over Springfield was 240 feet above the sea level. We have shown in a pre- 

 vious article that during the same period the highest flood level on the west side of 

 the Divide range was 280 feet above sea level. The flood at Westfield was at least 

 48 feet higher than that at Springfield. 



The question at once arises, Why was the water so much higher on the west 

 side of the range? The answer most frequently given is that the gaps through the 

 Divide range were closed, thus damming the water back and raising it to a greater 

 height west of the range. In the Westfield River gaj), upon the south side of the 

 river, there are two terraces. The lower one extends directly through the gap, at a 

 height of 199 feet above the sea. This terrace is made up of stratified deposits, con- 

 taining a large portion of clay. The beds extend, with the terrace, directly through 

 the gap. The continuity of the beds is evidence that the gap was open when the 

 deposits were made. These lower deposits, we have reason to believe, were made 

 during the early part of the Cliamplain period. It therefore appears that during the 

 early part of the Champlain period the gap was not completely closed by either drift 

 or trap rock. It should here be remarked that there is, on the right bank of the 

 river, just east of Morley's bridge, in the gap, a ledge of trap whose top is 21 feet 



