390 Scientific Intelligence. 



granite-gneisses, and the.Mamacoke gneiss are probably igneous 

 in origin and of very great age, and may represent p re-Cam- 

 brian masses. The Glastonbury granite-gneiss is of uncertain 

 origin. The Bolton, Brimfield, and Woodstock schists, Pomfret 

 phyllite, Plainfield and Scotland schists, and Putnam gneiss are 

 doubtless the metamorphic equivalents of sedimentary strata of 

 varying composition. The relation of these sediments to the 

 igneous gneisses has not been made out, and there is practically 

 no evidence in the field which determines the position of these 

 formations in the time scale. The discovery of fossils of the 

 Carboniferous period in the Worcester phyllite, which is proba- 

 bly the equivalent of the Pomfret phyllite, suggests a late Paleo- 

 zoic age for most of the schists east of the Connecticut River. 

 This view is strengthened by the evidence presented by the geo- 

 logical formations of central Massachusetts, where they have been 

 studied by Professors Emerson and Perry. However, there is 

 great similarity between the Bolton schist and the Hartland 

 (Hoosac) schist ; between the Woodstock and Plainfield quartz 

 schists and the Poughqnag quartzite ; and between the Brimfield 

 and the Berkshire schist. It is not at all impossible that more 

 extended investigations may reveal evidence that the metamor- 

 phic rocks of the Western Highland are related to those of the 

 Eastern Highland in time as well as in lithologic character. No 

 organic remains have been found in the crystalline rocks of east- 

 ern Connecticut, and so long as fossil evidence is lacking no 

 definite statements can be made regarding the stratigraphic posi- 

 tion of the different formations. The Eastford, Sterling, Canter- 

 bury, Maromas, Haddam, Stony Creek, Lyme, and New London 

 granite-gneisses, and the Preston gabbro-diorite, are intrusions in 

 earlier strata ; but were intruded before the time of the metamor- 

 phism that reconstructed the rocks of the entire state, and are 

 accordingly much modified by the development of gneissoid and 

 schistose features. The Hebron gneiss and the Middletown 

 gneiss are of uncertain origin ; the Willimantic gneiss is merely 

 a more injected phase of the Hebron. Pegmatite and amphibo- 

 lite are found cutting all of the formations mentioned above, and 

 occasionally small lenses of limestone are found. The Westerly 

 granite w 7 ith its various types in the southeastern part of the 

 state is later than the pegmatite, and is therefore the latest of all 

 the formations, with the exception of dikes of diabase, probably 

 of Triassic age, which extend in broken lines from the Sound to 

 the Massachusetts border." . 



The chapter on the Triassic by the senior author comprises a 

 clearly written and well illustrated summary of sixty-three pages 

 on the stratigraphy, fossils, igneous intrusions and extrusions, 

 and deformations of that system of rocks. A characteristic of 

 the volume as a whole is the judicial attitude toward unsolved 

 problems, the possibility of more than one opinion being repeat- 

 edly pointed out. In regard to the " conditions of deposition " 

 of the Triassic, however (pp. 166-170), the discussion is wholly 



