Geology and Mineralogy. 393 



glacial drift which largely mantles the state. It is to be expected, 

 therefore, that detailed study may result in minor shiftings of 

 such granite boundaries as are of a transitional character, and 

 possibly further determinations of age. 



As noteworthy features indicated on the present map and dif- 

 ferent from the earlier conceptions of the geology may be noted 

 the large areas of granite-gneiss which are regarded as mostly 

 intrusive of Paleozoic age and the reduced areas of gneiss which 

 are regarded as of pre-Cambrian age. 



In the accompanying bulletin a sketch is given of the history 

 of Connecticut geology and also credit for the sources. of informa- 

 tion. Especially to be noted is the following tribute to the work 

 of Percival done from 1835 to 1842 : 



"The more the modern geologist becomes familiar with the 

 involved structures and exasperating variations found within the 

 metamorphic rocks of the state, the more respect and admiration 

 he has for Percival's discrimination and skill in delineation. It 

 is doubtful if a more accurate discrimination of the various 

 members of a complicated series of crystalline rocks on field evi- 

 dence alone was ever accomplished" (p. 16). 



The latter part of the bulletin contains brief lithological 

 descriptions of the forty-two rock formations which are mapped. 



J. B. 



3. Second Biennial Report of the Commissioners of the State 

 Geological and Natural History Survey of Connecticut. Bulle- 

 tin JS"o. 9, State Geological and Natural History Survey. Pp. 23. 

 Hartford, Conn., 1906. — This report states the scope and plan of 

 the Survey, gives a synopsis of the bulletins already published, 

 of those accepted, and of the work still in progress. Plans for 

 future work in geology, botany and zoology are also outlined. 



In connection with the tabulation of expenses of the Survey 

 the Superintendent remarks: "The fact will be noted that the 

 compensation is in all cases very small in relation to the amount 

 of work done and the grade of ability and attainment of the 

 scientific men employed. The work has been indeed on the part 

 of all who have engaged in it a labor of love " j. b. 



4. Iowa, Geological Survey, Volume JCV1. Annual Report, 

 1905, with Accompanying Papers. Frank A. Wilder, State 

 Geologist. T. E. Savage, Assistant State Geologist. Pp. viii + 

 673, pis. viii, figs. 78, maps 14. Des Moines, 1906. — In this well 

 bound, we'll printed and well illustrated volume, besides the 

 administrative reports and recommendations and statistics of 

 mineral production for 1905, there are the detailed reports of the 

 geology of eight counties, viz : Winneshiek, Clayton, Bremer, 

 Black Hawk, Franklin, Sac, Ida, and Jackson ; also a report on 

 the plant's of Winneshiek County. The greater part of the state 

 has now been covered in detail. j. b. 



5. Limeless Ocean of Pre-Cambrian Time (A correction). — 

 Through a mistake of the author the conditions of an experiment, 

 cited by R. A. Daly on page 102 of this volume, were wrongly 



