IIsfTEOD UOTIOK 225 



ABRANOEMEISTT OF REPORT. 



A reference to the accompanying map (PL XXXI), illustrating the 

 geology of the lower part of the Narragansett Basin, will nhow that more 

 than half of the area investigated is covered by the waters of Narragansett 

 Bay and its many ramifications A large part of the remaining area, especi- 

 ally along the shore and on certain islands, is covered by sand and various 

 glacial and more recent deposits. The rock exposui^es occur chiefly along 

 the shore Much of the geology is necessarily uncertain, and the writer 

 claims only such an advance in the knowledge of the geological features of 

 the region as a careful study of the meager data will admit. In ^preparing 

 his report it seemed desirable to describe first the geographical distribution 

 of the various rock exposures, their lithological characteristics, and their 

 strike and dip, without any special reference to conclusions which might be 

 drawn from these (Chapters II- VI). This seemed preferable, since the 

 exposures furnish the basis for all conclusions, but the inferences drawn 

 are not always as imperative as in the case of other geological fields where 

 exposures are more frequent or admit of more ready interpretation. While, 

 therefore, a description of the exposures would have permanent value, the 

 interpretation of the geological structure might vary with the increase of 

 our knowledge of the geological data involved. Many localities, at present 

 still concealed by the soil, are likely to be exposed in the future by the 

 construction of roads or the digging of wells, foundations, and sewers. 

 The correlation of the beds exposed in various parts of the field, and the 

 conclusions concerning their relative age, receive special attention in the 

 later chapters of the report (Chapters VII-XI). 



The description of localities in geographical order is begun in Chapter 

 II with Dutch Island, the most western locality in the southern part of 

 Narragansett Bay in which fossils have been found. In going from this 

 island to Fox Hill and the northern part of Conanicut we remain in the 

 same series of rocks, and are better prepared to understand the differences, 

 stated later, between the Kingstown beds and the Aquidneck shales, which 

 occupy most of the remainder of the island. After this, Hope and Prudence 

 islands are described, these islands being more nearly in line of strike with 

 Conanicut than with other regions southward, and presenting rocks at least 

 of approximately similar horizons. 

 MON xxxiii 15 



