TITLES AND ABSTRACTS OF PAPERS 129 



COMPARISON OF THE EUROPEAN AND AMERICAN SILURIC 

 BY AMADEUS W. GEABAU 



(Abstract) 



During the summer and fall of 1910 much time was spent in the study of the 

 Siluric formations of England, Scotland, Sweden, Bohemia, and the island of 

 Gotland, and extensive collections made. Clear evidence has been obtained in 

 the field as well as from the study of the faunas that only two great divisions 

 of the Siluric are represented in Europe as in America. These are the Lower 

 and the Upper Gotlandian, corresponding to the American Niagaran and Mon- 

 roan. Q'he Middle Siluric or Salinian of America is unrepresented in Europe, 

 except possibly in the extreme west, there being throughout a marked hiatus 

 and disconformity between the Lower and the Upper Siluric. The discon- 

 formity is frequently well marked physically. The Lower Siluric comprises the 

 Lower Gotlandian of Sweden, the Llandovery, Wenlock, and Lower Ludlow 

 of western England, Etages (5, 7, and 8 (Lower and Upper Llandovery and 

 Lower Wenlock) of Norway, Etages Eei and Ee, of Bohemia, and corresponding 

 deposits elsewhere in Europe. The Upper Siluric is best represented in the 

 Baltic region, where it comprises the Upper Gotlandian, while in the Christiania 

 region it is represented by Etage E9 (Upper Ludlow) and by the Upper Ludlow 

 and succeeding continental beds of England and Wales. In Bohemia Etage 

 Efi represents this horizon, which has much in common paleontologically with 

 the Upper Monroan of North America. In the Baltic region the sediments are 

 mainly calcareous and the fauna of the Siberian type. In Great Britain the 

 sediments are to a considerable extent of deltaic and near shore, often partly 

 terrestrial, type, with an Atlantic fauna in parts, of which graptolites, stranded 

 on the mud flat surfaces, predominate. The Siberian fauna advanced westward 

 in Wenlock time, partly replacing the Atlantic fauna. It apparently entered 

 North America by the northern route, while the Atlantic fauna entered by 

 way of the Saint Lawrence channel. At the end of Lower Siluric time the sea 

 retreated from most of Europe and erosion followed. In Upper Siluric time 

 the sea readvanced from Siberia and from the Atlantic with a progressive 

 overlap of the various formations. Though many species characteristic of 

 Lower Siluric (Niagaran) have persisted in the two centers of distribution 

 and returned with the return of the seas, there were also many new types 

 which entered the regions for the first time. The spread of the continental 

 type of sedimentation in Upper Siluric time also caused a change in faunas, 

 introducing the river element to a consideriible extent. 



Presentefl in al:>stract extemporaneously. 



Discussion 



Mr.-M. Y. Williams: In the central part of the Niagara Peninsula of On- 

 tario, north of the town of Dunnville, the records of four gas wells indicate an 

 erosion channel in the top of the Niagara-Guelph formations. The thickness 

 of these formations is shown to vary from 2(X) to 250 feet, a channel 50 feet 

 deep and four miles or more across, with an easterly direction, being the nat- 

 ural explanation of the phenomena. 



