MODIFIED DRIFT ALONG MERRIMACK RIVER. 83 
made artificially in Concord. One mile south of Fisherville depot the 
course of the river was formerly in a westerly curve, passing around 
Goodwin’s point, two thirds of a mile from its direct course. At the 
west end of this detour it was fast undermining a long line of bluff 125 
feet in height. When the Northern Railroad was built, in 1846, the river 
was turned, to avoid bridging, into a new channel, by which its course 
was made straight, being shortened fully a mile. Its old channel remains 
filled with water, except at its south-west bend, which is nearly silted 
across; and the erosion of the bluff at times of freshet is greatly dimin- 
ished. Farther south, at about three miles above the city, the river 
flowed in two channels, of which the west one was largest, enclosing 
Sewall’s island. The railroad was built across this island, reaching and 
leaving it by embankments instead of bridges, for which purpose the 
west channel was dammed, when the river is said by Dr. Prescott to 
have swept away, to widen its east channel, a width of 20 to 25 rods of 
its bordering interval for two thirds of a mile. 
Dr. Prescott mentions that, in cutting the new channel across the base 
of Goodwin’s point, “the workmen, at the depth of about 12 feet, struck 
upon a bed or stratum of vegetable matter, consisting of leaves, branches, 
and trunks of small trees, the latter from three to six inches in diameter, 
the form of which was perfect, and the bark distinct. This vegetable 
deposit was found embedded in a stratum of fine blue sand, which at first 
sight was mistaken for blue clay, and was from one to three inches in 
thickness. The trunks and large branches were recognized as belonging 
to the natural order coniferz.” He also describes, from an excavation 
at the gas-works in Concord, supposed “fragments of the roots, trunks, 
and branches of trees. They were found deposited in a stratum of fer- 
ruginous sand (composed of sand and oxide of iron); and in some in- 
stances the fragments of roots and branches of trees were completely 
incased in a firm coating or crust of the oxide of iron and sand from one 
eighth to one half an inch in thickness.” This was at a depth of ten feet. 
It appears probable that these were cylindrical concretions of oxide of 
iron, which often show concentric rings, almost exactly imitating the 
annual layers of wood. These were found abundantly in the excavation 
for laying the water-works main, in 1872, near the south line of the city 
farm, and may be occasionally met with in any alluvial sand. 
