Dale.] 192 [January 3, 



seen by the sketch already given of that portion of the Island. It consists 

 of coarse grains of hyaline quartz, of a purple color, passing to deep blue and 

 black, with talc or mica (it is difficult to say which) ; the materials having 

 a schistose arrangement. The quartz bears a strong resemblance to peliom, 

 and constitutes a large part of the rock. The aggregate exhales an argilla- 

 ceous odor when breathed upon. This same rock may be seen at the mouth 

 of Fall River in Troy, R. I., where it is associated with an argillaceous 

 slate, passing into mica slate, and of a quite dark color from the carbona- 

 ceous matter it contains. At this place, this slate and quartz rock are con- 

 tiguous to granite; and they may be seen in Tiverton, lying directly upon 

 the granite." 1 



Prof. Chas. Hitchcock 2 states that the lowest rocks upon the 

 Island consist of " talcoid grits, often largely composed of grains of 

 sand and pebbles," and he remarks further : 



" Lower schists and conglomerates. — The only place upon the Island 

 where these are developed, is upon the promontory which is terminated by 

 Sachuest Point. Lithologically, the rocks are whetstone talcose schists, 

 grit, and soft slates, often containing many pebbles of quartz and grains, so 

 that they might be termed talcoid conglomerates. We noticed a few peb- 

 bles of red jasper among the constituents. This fact distinguishes this 

 group of rocks from the overlying conglomerates. These schists have a 

 direction of N. 20° E. and dip to the west 45° towards the coarse conglom- 

 erates at Purgatory. Cleavage and jointed planes are abundant in these 

 rocks upon Sachuest Pt. The age of these strata is probably older than the 

 Carboniferous series, though there is little difference in their external 

 aspect from that of the slates west of Purgatory. There are no beds of 

 coal or other fossils in them, and this exposure of them is an outlier isolated 

 by denudation from the same strata in Little Compton. Their thickness 

 upon Sachuest Pt. cannot be less than 1000 ft. These rocks have been 

 more or less metamorphosed, so that some of the pebbles appear like crys- 

 tals of quartz and feldspar in a crystalline schist." 



In passing from the eastern end of Sachuest Beach southwards 

 to Sachuest Pt. (Plate 1), near the beach the first outcrop is met, 

 a dark gray or black, coarsely stratified rock consisting of grains 

 of crystalline quartz, T V~i in. diam., with an argillaceous cement. 

 The waves wash out the argillaceous matter leaving a nodular 

 surface of quartz. The grains are held together in part by silica, 

 and in some places thus form a compact quartz rock traversed by 



1 This rock is now finely exposed at Tiverton in an abandoned quarry close to the 

 station. 



Geology of Aquidneck, p. 112, 113. 



