RHODE ISLAND COAL MEASURES. 181 



Section of Goat Rock Cliff — Continued. 



Feet. Inches. 



Shale, dark, slaty, a mere layer : .2 



Sandstone, gray o. 5 



Shale, with fossils, grading into sandstone 4 



Sandstone, slaty 6. 5 



Slate .75 



Sandstone, a hard gray rock 4. 5 



Grit, gray and hard 9 



Sandstone, gray, with plant steins, and traces of line-grained dark slate . . 2. 5 



Sandstone, subslaty, with plant stems 1 



Sandstone, flue grained, gray 6 



Shale, dark, slaty, trace .25 



Sandstone, gray 3 



Shale, dark reddish and slaty, with plant stems .75 



Conglomerate, gray and gritty, rather flue 2. 5 



Shale, black and slaty, with plant stems S. 5 



Sandstone, fine grained, dark gray, and in places gritty .4 



Shale, dark and slaty 5 



Sandstone, gray 10 



Conglomerate, fine aud gritty 2+ 



Talus of covered strata 30 



A noticeable feature hi this section is the frequent alternation from 

 sandstone to shales within a very limited thickness. The coarse conglom- 

 erate forming the crest of the ridge exhibits a variety of pebbles, as regards 

 both origin and secondary structures. The pebbles are chiefly a fine- 

 grained whitish quartzite, often presenting slaty cleavage, the discordant 

 direction of which structure in juxtaposed pebbles is evidence of mountain- 

 building in this geological province prior to the Carboniferous period and 

 subsequent to the formation of the quartzite, which is probably of lower 

 Cambrian age. 



Fossils. — The fossils found in place in this section are mainly imperfect 

 stems of calamites. In the drift in the vicinity of Goat Rock there have 

 also been found two species of determinative value, viz: Alethropteris and 

 Sigillaria volsii Bt. 



The latter plant is stated by Lesquereux 1 to be rare in the Coal 

 Measures of America, one specimen being seen by him from the Plymouth 

 F vein in Pennsylvania, a horizon near the top of the anthracite field. 



' Coal Flora, p. 492, PI. LXXII, fig. 11. 



