322 , ABSTRACTS 



Tallapoosa, and Anniston folios of the United States Geological Sur- 

 vey which are now in course of preparation. 



The Age of the White Limestone of Sussex County, New Jersey. J. E. 

 Wolff and Alfred H. Brooks. 

 The principal new observations contributed to this well-known field 

 by the authors were those indicating the presence of several longitudinal 

 faults along the boundaries between the Cambrian limestone and sand- 

 stone and the white limestone and associated crystalline rocks ; and the 

 discovery, at a new quarry in Franklin, of a crevice in the white lime- 

 stone which has been filled up by the overlying Cambrian arkose, which 

 contains bowlders and fragments of the white limestone, and fragments 

 of mica, feldspar and other minerals characteristic of the white limestone 

 Or associated rocks. From this and other localities, they conclude that 

 the Cambrian sandstone contains the debris of the white limestone 

 granite and associated rocks and explain the apparent transition between 

 the blue (Cambrian) and white limestones as due to fault brecciation 

 and shearing, and the apparent interbedding of the white limestone 

 and quartzite as due to the deposition of the latter on the irregular sur- 

 face of the white limestone, with local faulting in some places. They 

 conclude that the white limestone is of pre-Cambrian age and an inte- 

 gral part of the gneissic formation. This paper will appear in full in the 

 1 8th Annual Report of the Director of the United States Geological 

 Survey. 



Erosion at Baselevel. By M. R. Campbell. 



Some late observations by Mr. C. W. Hayes and the writer on the 

 solubility of quartz under atmospheric conditions and the writer's own 

 study of local baselevels in the Appalachian coal field seem to throw 

 some light on the question of the ultimate result of undisturbed ero- 

 sion, a result which has hitherto received but little attention from 

 physiographers. 



The conditions which seem to facilitate the solution of quartz are 

 those which would probably prevail during the final stages of the pro- 

 cess of baseleveling to a much greater extent than under ordinary con- 

 ditions of erosion ; consequently it seems probable that most, if not all, 

 of the waste of the rocks which is washed in from the surrounding 



