92 



SCIENCE. 



[N. S. Vol. V. No. 107. 



dent LeConte inquired about the relations 

 of the phenomena of the dirt bands described 

 by Agassiz years ago. Mr. Reid stated that 

 lie was uncertain exactly what was meant 

 by them, but he believed them to be the 

 same as the lines of stratification and to 

 originate as he had described, by the an- 

 nual burial of fine debris above the neve 

 line. 



The Pre- Cambrian Topography of the Eastern 



Adirondacks. J. F. Kemp, New York, 



N. Y. 



The discovery of outliers of Paleozoic 

 strata, oftentimes of very small area, far 

 within the Archean (perhaps in part Al- 

 goukian) complex of the Adirondacks, has 

 made possible the tracing out of some of the 

 Pre-Cambrian topographical features. The 

 recent completion of the topographical 

 sheets of the U. S. Geological Survey has 

 enabled us to illustrate the matter quite 

 fullj"^ and with comparisons of present 

 altitudes. It was shown that the early 

 Paleozoic sea apparently set up into nar- 

 row embayments in what were doubtless 

 old submerged valleys, which being now 

 indicated by the outliers, reproduce, in a 

 general way, some features of the old 

 topography. The abundance of Potsdam 

 boulders in the drift far in the hills leads 

 to the conclusion that the Potsdam was 

 probably more abundant in the interior be- 

 fore the ice invasion than now. 



After a brief introduction which cited the 

 older Cambrian deposits of Vermont and 

 the presumptive evidence that the Adiron- 

 dack crystallines were a land area, carved 

 by erosion during Cambrian time, slides of 

 topographic maps colored hypsometrically 

 as well as geologically were thrown on the 

 screen and the facts on which the conclu- 

 sions were based were thus illustrfiJted, due 

 allowance being made for faulting. Ci-ystal- 

 line limestones have largely determined the 

 valleys. 



In discussion M. E. Campbell inquired 

 if any variety in the basal Potsdam had 

 been noted in different regions, to which the 

 speaker replied that on the east and south- 

 east almost none were apparent. R. S. Tarr 

 remarked the parallel conditions in New 

 Jersey, where, however, folding has super- 

 vened. H. P. Gushing described similar 

 phenomena on the north side of the Adiron- 

 dacks, and especially outliers of crystal- 

 lines entirely surrounded by Potsdam, and 

 the projection of the latter into the moun- 

 tains where limestone occurred. F. D. 

 Adams instanced the same relations in 

 Canada around the old Lauren tian protaxis, 

 and in particular referred to the observa- 

 tions of Mr. Low in Labrador, showing very 

 strikingly the gradual encroachment of 

 Cambrian and Ordovician sediments into 

 embayments in the old crystallines. A. C. 

 Lane remarked the parallel phenomena in 

 Michigan. H. F. Reid inquired about the 

 amount to which the strata were tilted, to 

 which the speaker replied that the Paleo- 

 zoics were all notably flat and seldom 

 reached 15 degrees. 



The Society then divided into two sec- 

 tions. The one in which the petrographic 

 papers and those dealing with the crystal- 

 line rocks were presented assembled in the 

 rooms of Dr. G. P. Merrill of the Museum, 

 the others remaining in the original hall. 

 In the latter the first paper presented was 

 the following, the report for which and the 

 following is based on notes kindly taken by 

 Prof H. S. Williams and from the abstracts 

 furnished by several authors. 



On. the Southern Devonian Formations. 



Henry S. Williams, New Haven, Conn. 



The remarkable contrast between the 

 northern and southern Devonian formations 

 was shown. The former consists of a con- 

 siderable number of separate formations, of 

 differing kinds of sediments, and holding 

 separate and distinct faunas and together 



