498 J. D. Dana—The overflows of the flooded Connecticut. 
river. The sides and bottom of the estuary were of crystalline 
rocks, similar to those outcropping over the bordering regions. 
he sand-flats and mud-beds that were made in the great estu- 
ary, out of the material contributed from either side by the 
rivers of the era, constitute its Red-sandstone formation. 
The red sandstone of the area is now 300 feet above the 
sea-level near New Haven, and over 1300 in Massachusetts—a 
fact showing that, since Jurassic times, New England has been 
raised over its center at least a thousand feet more than along 
its southern coast. : 
ith the exception of the seaward slope thus occasioned, 
and the erosion by denuding waters, the area of the Triassic 
sand-beds might have remained till now a wide plain, with the 
river of the valley flowing through it in a deep channel of its 
own making, and emptying into the Sound at New Haven, had 
it not been that the deposition of the beds was followed, over 
the whole area, by subterranean movements that ended in tilt- 
ing them, making numberless long fractures to unknown 
depths, and filling the fissures so opened with melted rock. 
The sandstone was by this means left intersected by dikes of 
trap, along with adjoining hard-baked portions of its own beds 
which could stand wear a hundred fold better than other fee 
of the formation; and, as erosion went forward, the trap ikes 
became the trap ridges of the country, standing, with some 0 
the enclosing indurated sandstone, as high barriers between 
different parts of the sandstone area. 
A prominent line of these trap dikes divides the area, In 4 
north-and-south direction, from Mount Tom (1214 feet high) 
ear Northampton, Mass., to West Mountain (996 feet high 
three miles northwest of Meriden; the valley is thus divided 
into an eastern and a western section, the former three times re 
widest. This range is called in the following pages, the Moun 
om Range, and also Divide Range.* This range 1s continu 
south of the Meriden hills in a low ridge of sandstone to Moun 
Carmel (736 feet high); then, by another lower ridge of | i ‘ 
stone to East Rock (360 feet high) nearly abreast of New a 
ven city. - : at 
For the convenience of the reader of this and other eee 
papers on New England geology, by the writer, a map of the 
Mount" 
w Haven to Northampton was called the a 
wright in 1796 (Travels p. 8) ‘Looking ont 
, he made oes rae reat the West 
Cea 
op i , i i Over 50 ¥ 
to stop its further circulation. it still survives. 
h t ‘ournal. and Jj 
