JAXIAKY 18, 189r>.] 



SCIENCE. 



07 



brought out aduiirahly tlu' I'elations of the 

 hitcr sediments to tlie okler protaxis. 



40. The Surface Fdrmations of Southern New 

 JerM'y. Eoi.i.iN 1). SALisBrKY, Chicago, 

 111. 



The sui-f'ace formations of southern New 

 Jersey, which liaAe often been grouped to- 

 gether under the names, ' Yellow Gravel ' 

 and 'Columbia.' are believed to be divis- 

 ible into five formations, the oldest of which 

 greath' antedates the glacial period. The 

 several formations are unconformable on 

 eacli other and are believed to have been 

 widely separated in time of origin. These 

 formations were called the (1) Beacon Hill, 

 (2) Canasaucon (the spelling may be 

 wTong), (.3) Jamesburg, (4) Trenton and 

 the (5) Kej'port. It is impossible as yet to 

 say which are Columbia and which not, but 

 (2) is probably Pleistocene, and formed 

 durmg ice action on the north. Nothing 

 later than (3) is Columbia. The paper was 

 discussed by Warren Upham. 



41. New Forms of Marine Alga: from the Tren- 

 ton Limentone, ivith Observations on Butho- 

 graptus laxus, Hull. R. P. Whitfield, 

 New York. (The paper was read bj- E. 



O. HOVEV.) 



Certain fossils from Platteville, Wis., re- 

 ferred years ago by Hall with doubt to the 

 gi'aptotiles, were shown to be reallj' articu- 

 lated, marine algie, and referable to several 

 species. True corallines from the same 

 hoi'izon at Middleville were also described 

 which are mudi older than any hitherto 

 mentioned members of this group of plants. 



42. 0)1 the Honeycombed Limestones in the Bot- 

 tom of Lake Huron. Robert Bell, Ottawa, 

 Canada; (Read by H. M. Ami.) 



Tlie Limestones over a certain region in 

 the bottom of Lake Huron are extensively 

 eroded in a peculiar manner which the 

 wi-itt'r calls hcmeycombing and pitting. He 

 described this condition, the area within 

 which it is found, the depth of the water and 

 other conditions most favorable to its pi-o- 



duction and thin attcmi)tt'd toaccount forits 

 origin, enumerating various i)os.sible causes 

 which might suggest themselves, and giving 

 the most probable one, namely, a difl'erential 

 solubilitj- of the rock in the presence of 

 slightly acidulated Avater. Reasons in sup- 

 port of this view wi're stated. The geologi- 

 cal ages and the lithological characters of 

 the various limestones attacked were men- 

 tioned in trying to an-ive at the conditions 

 which produce the phenomena described. 

 The localizatiim of this form of erosion may 

 be attributed to a slight acichty of the water 

 in that part of Lake Huron, and reasons are 

 given for believing that an acid condition 

 actually exists. In addition to the consider- 

 ations due to the structure and composition 

 of the rock lying at the bottom of such water, 

 certain external conditions were mentioned 

 as favoring the lioneycombing process, which 

 appears to be still in active progress. Ex- 

 amples were given of somewhat similar 

 erosion elsewhere, but the typical honey- 

 comlting here described appears to l)e con- 

 fined to Lake Huron. The paper was illus- 

 trated by specimens and photographs. 

 43. On the Quarts-keratophijre and its A-^^o- 

 ciated Rocks of the Baraboo Bluffs, Wiseon'<in. 

 Samuel Wei dm an. (Read l)y J. P. Id- 

 dings.) 



In the vicinity of Barab(x>, Wisconsin, 

 occur acid por])hyritic rocks wliich corre- 

 spond chemically with quartz-keratophyres. 

 They exhibit under the micro.scopo fluxion, 

 spherulitic, poicilitic, and other structures 

 of volcanic rocks, and are associated with 

 volcanic breccias which show them to have 

 their origin in a surface flow. They are of 

 Pre-Cambrian age. since they rest upon the 

 upper Huronian (piartzite and are overlaid 

 by the Potsdam sandstime and conglomer- 

 ate. In some i)ortions of the area- they 

 have been completely changed to finely foli- 

 ated sericite schists through tlie orographii- 

 movement which elevated the quartzites to 

 form the Hlufl's. 



