. Geology of the Narragansett basin. Geology. WAMSUTTA OROUP. 157 loAv, as in the nose of a broad shallow syncline (see fig. 15). On the western arm of the area the dips vary from east to west Such marked inversion of strata warrants the explanation that the beds have been com- pressed into the fan structure by the marginal collapse of a more or less quaquaversal anticline which formed over the Hoppin Hill inlier It is owing to this extreme folding, together with the impei'fection of the expo- sures by reason of glacial drift, that the region is so difficult of interpreta- tion. Northward, nea
. Geology of the Narragansett basin. Geology. WAMSUTTA OROUP. 157 loAv, as in the nose of a broad shallow syncline (see fig. 15). On the western arm of the area the dips vary from east to west Such marked inversion of strata warrants the explanation that the beds have been com- pressed into the fan structure by the marginal collapse of a more or less quaquaversal anticline which formed over the Hoppin Hill inlier It is owing to this extreme folding, together with the impei'fection of the expo- sures by reason of glacial drift, that the region is so difficult of interpreta- tion. Northward, near Aimolds Mill, the apparent structure is indicated in the section, fig. 16 In the southern areas of red rocks in Pawtucket there is the most sat- isfactory reason for believing that the broad exposures of alternating red and gray rocks are due to close folding This disti^ict, indeed, furnishes a clue to the structure of the nearly vertical beds southward along the ws Arnolds M/// I Goat Rock /huff *. ' Fig 16 —Geological section m the Arnolds Mills region western margin oi the Narragansett Basin, in the Cranston beds, and in the equivalent Kingstown seizes, described by Dr. Foerste in another section of this monograph This same field, showing the red and gray Carboniferous strata folded into isoclinal relations, afi'ords strong evidence for believing that the Wam- sutta series, in the main basin at least, was not folded until the deposition of the Coal Measures, and that the entire thick section of sediments in the basin underwent plication after the period of deposition. All the facts from various points in the field support the view that there was but one period of elevation, and not two, as was formerly thought by Edward Hitchcock. There are a few disturbances along the northern margin in the Wamsutta area, which have been thought to indicate an upturning of the red series before the deposition of the Coal Measures in that section, but to my mind the evidence is not clear
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