REVIEWS 



403 



Middle 



Hamilton 



lower members are still tentative. The beds rest unconformably on 

 Silurian rocks ranging in age from Salina to Cobleskill or younger. 

 The revised classification follows: 



TT /Port Lambton (probably Portage or Chemung) 



iHuron shale (probably Genesee) 

 Ipperwash limestone 

 Petrolia shale 

 Widder beds 



i i.vnuuie< 



Devonian \ [Olentangy shale 



Delaware limestone 

 .Onondaga limestone/Onondaga limestone 



ISpringvale sandstone (local fades) 

 rOriskany sandstone 

 1 Lower < Helderbergian (wanting or possibly represented in the 

 I Detroit River series) 



From 2 to 10 sections are given in each of the 12 counties included 

 in the area. The paleontology has been worked out with great care and 

 each section is accompanied by its fauna classified by horizons. Of 

 the species given, 350 are listed from the Hamilton beds alone and 347 

 from the Onondaga. Largely on faunal evidence the Springvale sand- 

 stone is considered a local facies of the Onondaga instead of belonging 

 to the Oriskany. 



There is a chapter that summarizes present knowledge of the devel- 

 opment and migrations of the Devonian faunas in this region and a 

 chapter of bibliography on the Devonian of the eastern continental area. 



W. B. W. 



Central Connecticut in the Geologic Past. By Joseph Barrell. 



Connecticut Geol. and Nat. Hist. Survey, Bull. 23. Pp. 44, 



figs. 9. 

 This bulletin is a study of the extent to which ancient geologic 

 structure and physiographic features may be reconstructed from data 

 now available. Technicality has been avoided in an attempt to make 

 the report available for general reading. To further this plan the his- 

 torical geology is taken up in reverse of the usual order. 



A number of wholly new structure sections are of chief interest. 

 These sections reproduce the structure for each geologic period since 

 late Paleozoic times. There is a departure from conventional structure 

 sections in that clouds and the landscape of the background are added. 

 These features may be of aid to readers untrained in geology. 



