Fbbuuary 6, 1903.] 



SCIENCE. 



223 



comparing such a ring-plain as Theopliilus, 

 for example, with the Hawaiian ealderas 

 studied by Dutton, we are led to assign to 

 these lunar rings an origin similar to that 

 of terrestrial ealderas. 



Evidences of Post-Newark Normal Fault- 

 ing in the Crystalline Rocks of South- 

 western New England: Willlvm H. 

 HoBBS, University of Wisconsin. 

 The stud}% in 1899, of the Newark area 

 of the Pomperaug valley in Connecticut 

 disclosed conditions of deformation which 

 have made it possible to work out, in part 

 at least, the structure of the crystalline 

 rocks surrounding the Newark basin. The 

 key to the structure has been sought and, 

 it is believed, found in these areas where 

 the areal relations seem most complex, or 

 where, in other words, a large number of 

 formations are found in small masses 

 within a very limited area. Such areas 

 of complex areal relations have generally 

 been regarded as ill-adapted for structural 

 studies. They have also been generally 

 neglected for the reason that the deter- 

 mination of their structure would be time- 

 consuming, and, when once determined, 

 could hardly be represented upon geology 

 ical maps of the ordinary scale. The 

 studies here under consideration have 

 shown that, complex though they may be, 

 the very complexity of these areas will 

 generally allow of but one theory of their 

 structure, provided the data collected are 

 sufficiently complete. On the other hand, 

 areas of the crystalline rocks in which 

 formations are represented at the surface 

 by large masses are apt to allow of a num- 

 ber of theories of interpretation, any one 

 of which may furnish an adequate explana- 

 tion of the facts observed. It has been by 

 the detailed study of a number of widely 

 separated areas of excessively complex 

 areal relations that the conclusions here 

 stated have been reached. 



It was shown that the area of south- 

 western New England is one of complexly 

 jointed and faulted, as well as of complexly 

 folded, rocks. The sj^stem of faults affect- 

 ing the area is found to be oriented like the 

 system of joints. The throws along fault 

 planes, while generally small, are, owing 

 to the great number of faults involved, by 

 their cumulative effect of great impor- 

 tance. Methods have been developed by 

 which the fault system of an area may, 

 under favorable circumstances, be deter- 

 mined from observation in the field. 



A Record of Post-Newark Depression and 

 Subsequent Elevation within the Area 

 of Southwestern New England: Wni- 

 LiAM H. HoBBS, University of Wisconsin. 

 AVithin a belt some twelve miles in 

 length, lying between Sheffield, Slass., and 

 Falls Village, Conn., there are revealed 

 some peculiar conditions of the impregna- 

 tion of dolomite by silica. The trunk lines 

 for the introduction of the silica are shown 

 to be a system of joint- and fault-planes 

 clearly connected with the Post-Newark 

 deformation of the area. Evidence is not 

 lacking that surface conditions widened 

 the joint fissures previous to the infiltra- 

 tion and cementation by silica. A meas- 

 ure of time is thus secured within which 

 the cycle of subsidence, cementation and 

 elevation, must have been included. 



Criteria Requisite for the Reference of 

 Relics to a Glacial Age: T. C. Chamber- 

 LiN, Chicago University. 

 What constitutes good grounds for re- 

 ferring relics (human, in particular) to 

 a glacial age, and the chief sources of error 

 in making such reference were discussed 

 under the following sub-topics: Evidence 

 to be sought in the glacial formations 

 themselves; evidence from the bowlder 

 clays; evidence from assorted drift in- 

 cluded in till and moraines ; evidence from 



