632 GEOLOGY OF OLD HAMPSHIRE COUXTY, MASS. 



THE FACTORY VILLAGE CHANNEL. 



The map shows very clearly the broad watercourse which bends north 

 from Turners Falls and then turns sharply southwest and runs, its l^auks 

 and bottoms well preserved and uneroded, to where it widens out into the 

 broader sand plain of the south part of Greenfield. 



This passao-eway was set free by the ice earlier and was occupied by 

 the Connecticut longer than the passage farther north through the Ber- 

 nardston Pass, and a vastly greater body of material was l^rought into the 

 Deerfield side valley by this way than by the northern one. 



THE HIGH TEREACE PLAINS IN THE SOUTH OF GREENFIELD AND NORTH OF 



DEERFIELD. 



At the end of the Champlain period a Ijroad unljroken plain extended 

 from the south part of Greeniield southward through Deerfield, out of which 

 the channel of Green River and the great basin of the Deei"field River have 

 been eroded. Tln-ough the southern part of Greenfield and the north of 

 Deerfield, to near the point where the Deerfield River leaves its rocky 

 gorge, the deposits forming this plain are laminated clays, often 20 to 33 

 feet thick, overlain by sands reaching a thickness of 80 feet, often hori- 

 zontally laminated in their lower portions and cross-bedded on a grand 

 scale above. 



The section exposed on the south side of the road from Greenfield 

 to Franklin Park,* in the hillside immediately beyond the bridge, is very 

 striking. In the bed of the ])rook the reefs of bright-red sandstone rise 

 above the water and run under the bank. On this, in the vertical wall facing 

 the stream, is exposed 20 feet of till, dull red and made almost entirely of 

 comminuted sandstone. This is covered by 20 feet of horizontally bedded 

 clay, in layers 1 inch thick on an average, and as one goes up the hillside 

 the clays are seen to l)e capped by a great thickness of fine sands, hori- 

 zontally and distinctly laminated, at least 55 feet thick. The upper 20 feet 

 is made up of sands with flow-and-plunge structure and cross-bedding on a 

 grand scale. The section is exposed for 200 feet, and the sands dip with 

 varying and suddenly-changing angle 0-30°, always toward the east. 

 These latter sands ^-ary from fine to coarse. 



'The broad, perfect plain (1 s U) southwest of Greeufield aud extending to the Deerfield River. 



