MODIFIED DRIFT ALONG MERRIMACK RIVER. // 



wide, sandy "pine plains," so called because their principal wood-growth 

 consists of white or pitch pines. These are sometimes accompanied by a 

 thick and tangled undergrowth of scrub oaks, which, with the pitch pine, 

 flourish best on the barren plains. Their surface is very level, with a 

 regular but very slight slope, v/hich amounts to nearly the same as the 

 descent of the river. In some places this may be finely seen, as at Con- 

 cord, where a level set at the same height with the plain on the east side 

 commands a view of its edge for three miles along the river, in which dis- 

 tance it is seen to slope only a few feet, with no undulation to break its 

 straight line. 



It is worthy of notice, that in this entire valley, including Pemigewas- 

 set river, no important deltas are found. This is in remarkable contrast 

 with the Connecticut valley, where the regular line of the river's highest 

 alluvium is hardly traceable, or is less readily seen much of the way, be- 

 cause of the extensive higher deposits of tributary streams. In this valley 

 such deposits have helped to fill extensive areas, as in Concord, for which 

 it would seem that otherwise the supply must have been deficient, and 

 sometimes they slightly increase the height of the upper terrace, but in 

 no place do they form, as on the Connecticut, frequent and well marked 

 terraces above this normal line. The Merrimack valley is wider than 

 that of the Connecticut, giving room for its ample plains ; and its sides 

 slope more gently, forming lower ranges of hills. Its tributaries partake 

 of the same character, and also have a less rapid descent than in the Con- 

 necticut basin, allowing the deposition of large amounts of alluvium along 

 their course, as on Baker's, Contoocook, and Suncook rivers. The modi- 

 fied drift of the Merrimack is rendered more simple, but not less instruc- 

 tive, by being free from the confusion of associated tributary deposits. 



At Franklin the upper terrace is well shown upon both sides of the 

 valley. It has considerable fall in a short distance here, being 445 and 

 440 feet above the sea at the north side of Webster brook and Winnipi- 

 seogee river, and descending in less than a mile to 430 and 420 feet at 

 their south sides. The mouth of Winnipiseogee river is 269 feet above 

 the sea, the Pemigewasset having descended nearly 30 feet in its last 

 mile, so that the upper terrace here has a height 150 to 175 feet above 

 the river. The highest alluvium for eight miles northward, extending 

 through Sanbornton and including the large plain north of Salmon brook, 



