224 GEOLOGY OP THE NARRAGANSETT BASIN. 



there. While in the midst of this work he was called away from this field 

 to another division of the Survey. Only about four months had therefore 

 been spent by the writer in this southern portion of the basin previous to 

 the present summer (1895), when two additional months were occupied in 

 field work. This report is the outcome of the observations made at these 

 various times. No one can understand better than the writer both the short- 

 comings of the report and the difficulties of the field. While exposures are 

 numerous in various parts of the basin, chiefly along the shores of the main- 

 land and the numerous islands, they are so widely separated by the arms 

 of the bay and by broad areas of sandy soil that an interpretation of the 

 structural relations existing between the exposed rocks is exceedingly diffi- 

 cult, if not impossible. Under the circumstances, however, it is hoped that 

 the report will at least add something to our knowledge of the basin and 

 furnish a basis for future labors and rectifications. 



As the result of much thought and care in the study of the exposures 

 actually found, although within a limited time, the writer will express the 

 following opinions: Isolated exposures of small extent, unless within an 

 area of frequent exposures, are apt to be more misleading than serviceable 

 in the identification of horizons, owing to locally sudden lithological 

 changes, especially in areas occupied by the Kingstown series. Greatest 

 weight in making out geological horizons and the order of succession should 

 always be given to long lines of exposure. It is not considered advisable 

 to attempt a division of the Carboniferous rocks into separate geological 

 horizons until an acquaintance is made with the scattered Carboniferous 

 exposures over a very large area — in fact, over at least half of the area 

 investigated — since otherwise the importance of features of only local value 

 is easily magnified. 



It may seem trite to express such opinions, in view of the advanced state 

 of methods of geological investigation, but these remarks are especially 

 pertinent to the Narragansett Basin, where the investigator of a limited 

 field, especially in the dubious country in southern Aquidneck, is liable to. 

 go astray on account of the absence of exposures at very critical points. 

 Nowhere are isolated small exposures more liable to influence opinion as 

 to the geological succession of neighboring larger rock masses than here, 

 and nowhere is the possibility of consequent erroneous views greater, but 

 the attempt has been made to overcome these difficulties, and it is hoped 

 with at least a measure of success. 



