392 Scientific Intelligence. 



accepted. As yet the writer has heard no dissent from these 

 conclusions. 



If the hypothesis of fluviatile origin be accepted, it may be 

 further stated that the character of the sediments indicates an 

 origin in down-sinking basins with no necessary connection with 

 the sea, and in those north of Virginia, under a sub-arid climate. 



The last chapter in the volume, on the glacial geology, by the 

 junior author, gives a clear presentation of the problem pre- 

 sented by the surface features of the state and how the solution, 

 step by step, has led to one of the most astounding conceptions 

 in geology, — that of a continental ice sheet which in very recent 

 geological times spread from Canada over the northern portion 

 of the United -States, incidentally burying the entire land surface 

 of Connecticut. 



In conclusion it is not too much to say that this volume will do 

 more toward the dissemination of first hand geological knowl- 

 edge through the state than all papers previously published, and 

 in all geological instruction will be found by the teacher within 

 the state an invaluable adjunct to the text-book. J. b. 



2. Preliminary Geological Map of Connecticut ; by Herbert 

 Ernest Gregory and Henry Hollister Robinson. Accom- 

 panied by Bulletin No. 7, explanatory of the map. Connecticut 

 State Geological and Natural History Survey. Hartford, 1907. — 

 Since Percival's map of 1842, no geological map of Connecticut 

 has been published until the present. As a consequence, to all 

 except specialists in Connecticut geology the districts outside of 

 the Connecticut valley have formed a terra incognita. This map 

 is, therefore, a most welcome addition to geological literature 

 and will be of great value for educational purposes, especially 

 within the state. On account of the lack of detailed surveys 

 over much of the area, it is stated by the authors in the accom- 

 panying bulletin to be a preliminary map only, and to be open to 

 correction upon the completion of such detailed surveys. Never- 

 theless it will take its place as an important contribution to Con- 

 necticut geology. 



The difficulties of the region are such as those geologists work- 

 ing in more favored regions can with difficulty appreciate, and 

 account for the interval of sixty-five years between the first and 

 second geological maps of the state. These are due in general, 

 first, to the high, degree of metamorphism of all but the Triassic 

 of the valley of the Connecticut, which has destroyed all fossils 

 and obscured the original nature and relations of the formations. 

 As a result the age of the greater number of formations is 

 unknown and such as are known have been determined by trac- 

 ing them into the state. A second difficulty arises from the com- 

 plex and repeated deformations to which the region was subjected 

 in Paleozoic times and the faulting of the Mesozoic. Again, the 

 tangle of granitic injections, more or less gneissoid, which on 

 their margins are sometimes interfingered and infiltrated with 

 the surrounding schists for miles; and lastly the covering of 



