LIMESTONES AND CONGLOMERATES 471 



eastern ranges, L and Q representing the limestones and quartzites. I 

 do not know whether the staurolitic mica schist between the two lime- 

 stones is of inferior age. The staurolite crystals are profusely abundant 

 and furnish both the red and black varieties known as from Mink pond 

 (now Pearl lake), in Lisbon. The natural continuation of metamorphic 

 influences might enlarge the slender staurolites of the upper slate. This 

 area in the east part of Lisbon is represented on our map. Similar 

 rocks to the south of this district have been described as newer than the 

 quartzite. 



The Conglomerates 



First of all is the one termed " auriferous." My attention was turned 

 to it in my very first visit to this region in 1868. Being very durable, it 

 has resisted disintegration, and its stratification marks are well pre- 

 served, so that it is a safe guide to the stratigraphy of the district. The 

 pebbles in it are chiefly of quartz, commonly less than an inch in diam- 

 eter; rarely the material is of jasper, chlorite, or hornfels, the frag- 

 ments having a maximum breadth of 2 inches. In some localities the 

 pebbles have been elongated, flattened, and distorted, and I have men- 

 tioned instances where they have been fused into a homogeneous schist. 

 A small amount of gold has been proved to exist in it in certain favored 

 localities, whence the name, and the thickness is usually 100 feet. The 

 narrowest is 10, and when it reaches 300 or 500 feet there is a suggestion 

 of duplication by folding. Over the principal area of distribution it is 

 always found on the hilltops, because of its greater durability. 



The part which is truly characteristic and uniform commences ab- 

 ruptly in Lyman, southwest from Youngs pond, and may be traced into 

 Bath about 5 miles, in 2 lines. A faulted segment of the same, repeated, 

 extends equally far to the north, reaching to Mill brook, but it does not 

 extend so far south by a mile. 



The areal distribution of this formation illustrates the nature oF the 

 forces which have variously disturbed its original continuity. As a 

 rule, the dip is nearly vertical ; the continuous band has been broken 

 into many segments, most of which have been curved or faulted, or 

 both. Apparent discontinuity may sometimes be the result of a drift 

 covering. Not only is the conglomerate itself thus disarranged, but the 

 associated formations must be similarly affected to a considerable extent. 

 Segments may be pushed out of line by the presence of some refractory 

 mass on one side, and every kind of orographic movement may be looked 

 for. The result of the disturbances is the existence of a gigantic breccia, 

 or mosaic, whose pieces may not be firmly cemented together. Curved 

 strata will prevail until the strength of the rock gives way, and in many 



