190 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
Road bridge in Attleboro shows two or three fine examples that have 
been described and figured by Woodworth (d, p. 176-177). A bed 
of fine sandstone twenty feet thick has been excavated to the under- 
lying coarse pebbly beds and then the eroded area covered with 
coarse sands. A few yards farther north another exposure by the 
roadside shows erosion following the deposition of red shale and 
preceding the deposition of gray beds. Fragments of the red shale 
are included in the overlying gray sediments. 
Relations to Subjacent Rocks. The contact of the Carboniferous 
sediments with the underlying rocks is seen at several places along 
the border. On the western side of the basin two and one-half miles 
north of Natick, R. I., the basal beds rest upon the Precarboniferous 
terrane. ‘They EE many angular fragments and rounded pebbles 
derived from the older rocks, the material of the pebbles varying with 
the character of the underlying floor (Foerste, b, p. 253). On the 
eastern side of the basin at Tiverton the contact between the granite 
and the overlying Carboniferous rocks is well shown. : The clastics 
consist of interbedded arkoses and coaly shales, sometimes one and 
sometimes the other in contact with the granite (ibid., p. 272). Where 
arkose occurs along the border it is generally found near those places 
where the immediately underlying rocks consist chiefly of granite 
(ibid., p. 375). The arkose and the basal conglomerate show that 
the Precarboniferous rocks were subjected to protracted subaerial 
disintegration before the deposition of the sediments. 
No polished nor striated surfaces nor other evidences of ancient 
glacial conditions are exhibited by the various observed contacts. 
Summary of the Narragansett Basin Series. (1) Conglomerates, 
sandstones, and shales, with some coal beds, occur interbedded 
at various horizons, but the coarse conglomerates occur at the top 
of the series and are confined to elongated synclinal areas. 
(2) Contemporaneous acid volcanic rocks are associated with the 
series. 
(3) The upper conglomerate becomes coarser toward the south. 
(4) Banding is the prevalent type of bedding. 
(5) Lenses are relatively uncommon and present the same charac- 
teristics noted in the Boston and Norfolk Basins. 
(6) Cross-bedding and ripple-marked surfaces occur occasionally. 
They show that the strata are not inverted. 
(7) Two well-defined examples of local unconformity appear at 
Attleboro. 
(8) The sediments were deposited on a terrane deeply disintegrated 
by subaerial agents. There is no evidence of ancient glacial scoring. 
