LISBON-SWIFTWATER COMPLEX 4?? 



In passing from North Lisbon in a northerly direction over the hills, 

 the granite (Bethlehem) reaches nearly to the top of what may be called 

 the north Walker hill, and it has evidently increased the tilt of the strata 

 by its protrusion, and has silicified the adjacent schists. Sericite schists 

 and a sprinkling of hornblende crystals in other strata come next, fol- 

 lowed by a chloritic conglomerate with flattened pebbles, which may 

 be located at the intersection of the town line by a carriage road. To 

 the west is a considerable mass of diorite before reaching extensive argil- 

 lites forming the eastern flank of the Blueberry range. 



Going west from North Lisbon, the limestones are overlain by sand- 

 stones, the conglomerate under the bridge, drab quartzites and mica 

 schists carrying scant calcareous strata, all dipping about 50 degrees 

 northwesterly. Then for half a mile no ledges are exposed, because of 

 the presence of the south Walker Hill morainic mass. Then may be 

 seen slaty rocks, including the well known whetstones, a fourth of a 

 mile wide, with a smaller inclination. The last mile of this section to the 

 Blueberry slate range is mostly taken by green chloritic schists and an 

 igneous mass of hornblende. . 



The next section, up the Whipple brook on the "Oregon road," 

 discloses only hornblende rock, with some limestone at the start, most 

 of the rock being covered by the quaternary floodplain. It is presumed 

 that some of this hornblende schist may have been altered from lime- 

 stone, and thus not have been originally an igneous rock. 



The next traverse across the complex lies along the courses of Salmon 

 hole and Mill brooks, as portrayed in plate 42, figure 6. Above or to 

 the west of the calico conglomerate are dark micaceous quartzites, with 

 irOn ore nodules and black argillites dipping 45 degrees northwest. The 

 conglomerate by a school-house at the Ammonoosuc crossing is close at 

 hand; and not very far to the south, but not on the section line, is a 

 white silicious rock carrying many minute curvatures suggestive of a 

 possible different interpretation of the dip. West from the school- 

 house are green quartzites, chlorite phyllites * and hornblendic layers. 

 The coarse conglomerate near the mouth of Mill brook is interstratified 

 with thin layers of hard green schists, and there is a notable develop- 

 ment of this green rock before reaching the black and drab argillites. 



The next traverse line is indicated in plate 42, figure 8, a general sec- 

 tion from the Bronson limestone quarry in the east part of Lisbon, 

 through the village to Parker hill, and about 3 miles south of the section 

 represented in figure 5. Only one of the bands of limestone and quart- 

 zite is visible, and its position and relations to the staurolite mica schists 

 are quite different. A faulted block is suggested both by the vertical 



*No. 127 of the Educational Series, U. S. Geol. Survey. 

 LXI— Bull. Geol. Soc. Am., Vol. 15, 1903 



