211 



transverse thrust or a tendency to slieur. Hut, unfortunately, 

 there is at this point a complete iiiatus of nearly 300 feet 

 in the outcro[)s ; and the full extent and form of the fold 

 can not be made out. That the east-west strike is quickly 

 resumed is shown, however, by the ledges between this and 

 AVest Hingham Station ; and it is especially satisfactory to 

 find that the very first exposures show the thick bed of gray 

 sandstone, the most unique bed of the entire sedimentary 

 series, and therefore the most to be relied upon in correlation. 



About 100 feet back of the school house and 400 feet from 

 South Street, an artificial excavation has uncovered the 

 abrupt face of a ledge which shows 75 feet of greenish gray 

 sandstone (5) with distinct slaty partings, dipping S. 70° 

 beneath 40 feet of conglomerate (5) ; while fragments in the 

 soil indicate tiiat the conglomerate is overlain in turn by slate 

 (4). The conglomerate and sandstone are easily traced to 

 the westward several hundred feet, where they form the 

 northern portion of a group of ledges aflTording the following 

 nearly continuous section, beginning on the south : — granite, in 

 several obscure outcrops ; then, after an interval of a hundred 

 feet or more, with one uncertain exposure of melaphyr, come 

 without an appreciable break, 120 feet of melaphyr (2) ; 120 

 feet of fine conglomerate and sandstone (3) ; 50 feet of slate, 

 mostly gray, but changing to red on the north (4), the red 

 rock being well exposed behind one of the houses on South 

 Street; 40 feet of conglomerate (5) and neai'ly 100 feet of 

 gray slaty sandstone (5). The isolated and obscure outcrop 

 of gray slate a few yards from the line of South Sti-eet (see 

 map) undoubtedly marks the extension of the great bed (fi) of 

 the Ilersey Street section ; and on the north side of the street, 

 in the rear of the second house from West Hinjj-ham Station, 

 we have a satisfactory exposure of the conglomerate (7) which 

 borders this slate on the north. The only remaining outcrop 

 in this direction lies some 300 feet farther to the northwest, 

 beyond the railroad and on the north side of the brook. It 



