SCIENTIFIC SURVEY. 305 



II. Geology of the St. Croix and Chepedneck Rivers. 



Below Devil's Head in Calais, on the west bank of the St. 

 Croix river, the rock is granite and syenite. Above this headland 

 indurated slates appear, forming a very narrow border to the gran- 

 itic rocks, so narrow that it escaped our notice last year. This 

 border extends, with a single interruption, to Milltown. It 

 is never over a few rods in width. Near the lower steamboat 

 wharf are two dikes of traps cutting through the slates or schists. 

 More of the schists appear at Salmon Falls, but the last traces of 

 them disappear at Milltown. The river runs through a gorge in 

 this rock below and at the Mills. Beautiful specimens of pyrites 

 were shown us which were said to have come from beneath the 

 Union Bridge. If abundant, this deposit may be very valuable. 



A band of syenite crosses the St. Croix above Milltown, showing 

 itself for five miles along the river and railroad. At Baring station 

 and on the summit level of the railroad in St. Stephens, N. B., the 

 syenite is rendered beautiful by the occurrence of micaceous 

 nodules. The nodules are black, but the stone is white. These 

 nodules may at one time have been pebbles, and the agency that 

 changed the sedimentary rock into syenite, may not have oper- 

 ated long enough to have obliterated the sedimentary character of 

 the rock. The nodules are not as regular and handsome as the 

 so-called " petrified butternuts" in the concretionaiy granite of 

 northern Vermont. 



There is considerable syenite in the granite about Calais, and it 

 is possible that an accurate knowledge of its distribution might 

 assist greatly in determining the truth of the theory that these 

 rocks were once sedimentary. If the various masses of syenite 

 are disposed like stratified beds in the granite, the theory would 

 be confirmed. The syenite seems to run into the .granite like a 

 spur or a bed, on the road east of the principally inhabited part of 

 the city towards Vose lake. On Bog brook in Ilardscrabble, in the 

 same rock, is an immense mass of white quartz and chalcedony, in 

 which specks of gold may be found. On the summit of Macwa- 

 hoc mountain the granite rocks have been beautifully embossed by 

 the drift agency, looking like a great number of large haycocks 

 crowded together. It is not common to find so good an example 

 of these embossed ledges in this part of the State. Small pieces 

 of calcite have been found in the west part of Calais. Small pieces 

 of gypsum have been picked up on the shore near the steamboat 

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