MODIFIED DRIFT ALONG MERRIMACK RIVER. 8/ 



road at the point where it reappears in Bow, one fourth of a mile north of 

 Robinson's station. Here the water-worn gravel, containing none but 

 rounded pebbles, the largest of which are two or three feet in diameter, 

 forms a well defined, anticlinally stratified ridge about 40 feet high, which 

 is entirely overlaid by the later sand deposit of the ordinary terrace. 



Fig. 20. — Section of Kame overlaid by Sand, i Mile north of 

 Robinson's Station. Scale, i inch=5o feet. 



Thence the series extends for a mile in a single ridge, which is partially 

 and at some points wholly covered by the fine alluvium. In the next 

 mile we have two ridges nearly parallel, but somewhat irregular in course 

 and in height. The intervening hollow contains a small pond. These 

 ridges form the east border of wide plains, which have nearly the same 

 height with the kames. The sand of the plains is shown to be the most 

 recent deposit by its superposition. It appears that, after the gravel 

 ridges had been formed, great amounts of sand were swept into the val- 

 leys ; but spaces nearly enclosed between parallel ridges were often pro- 

 tected from this deposition. In the subsequent excavation of a large 

 portion of this sand by the river, producing the lower terraces and its 

 present channel, these coarse ridges have been a barrier protecting the 

 plains on their west side. Opposite the mouth of Suncook river, the 

 eastern of the two ridges lies on the south-east side of a small brook; — 

 here we again found for a few hundred feet numerous angular rock-frag- 

 ments, of dimensions from one to two and a half feet, while other por- 

 tions, so far as seen, were of water-worn but often very coarse gravel. A 

 short distance farther south the series is suddenly interrupted, and its 

 direct course is occupied by a high, ledgy hill. An irregular high terrace 

 of gravel and sand on its east and south-east sides may represent the 

 kame. After a mile the series reappears in its characteristic ridges, and 

 continues five miles quite irregularly and of varying material, but plainly 

 one connected series to its next gap, which begins opposite Martin's 

 Ferry. 



