BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 6, pp. 297-304, PLS. 13-15 MARCH 25, 1895 



HONEYCOMBED LIMESTONES IN LAKE HURON 



BY ROBERT BELL 



(Read before the Socictij December 29, ISO.'i) 

 CONTENTS 



Pago 



Area oi occurrence and conditions 297 



Physical characteristics of the eroded rocks 298 



Age and attitude of the eroded rocks 299 



Erosion forms in relation to variety of rock 299 



Possible origins of the erosion 300 



Borings of mollusks oOO 



Action of sponges and algic 301 



Wearing action of peb])les 301 



Acid water the probable cause of the erosion 302 



Sulphuric acid in the water and its source 303 



Conclusions 304 



Area of occurrence and Conditions. 



The limestones in the bottom of a certain portion of lake JFuron are 

 undergoing a peculiar kind of erosion, which, from want of l)etter terms 

 to describe the process, may be called honeycombing and pitting. 



The portion of the lake in which this phenomenon is most prevalent is 

 that around Grand Manitoulin island, the Indian peninsula and in J^ig 

 gap, which lies between them and connects the main body of the lake 

 with Georgian bay. This curious form of erosion appears to be progress- 

 ing most rai)idly under a considerable depth of water, say, from 50 or 

 100 feet, down to greater de})ths, ])ut it may also be going on in shallower 

 water. The existence of the honey(;ombe(l limestone all over the bottom 

 of this jiart of lake Huron is well known, to every one living in tlie 

 vicinity, and especially to the fishermen, to whom it is a great source of 

 annoyance from their nets catching upon it. Visitors cairy away speci_ 

 mens of it every summer as curiosities, but, so far as the writer is aware 

 no one has yet described its occurrence, att(Mnpted to explain its cause, 

 or reported a similar condition elsewhere. Tin; i)henomenon therefore 

 appears to be rare, if not unique, and worthy of a des(!ription from a 

 geologic standpoint. 



XLII-Hii.i,. Geol. Soc. Am.. Vol. 0. 1894. (297) 



