HAUKER : PETKOLOGICAL JiOTES. 
423 
nearly an iiicli across, being due to the dissolving away of the 
carbonate of lime under pressure from the angles of neighbouring 
pebbles. The specimen, as found, was not in contact with any other 
boulders, and it is a matter of speculation at what stage in the history 
of the boulder it was subjected to tlie pressure in question. The 
fracture of boulders is well-known in some districts, and has been 
recorded by various German geologists'*', but the solution of a lime- 
stone boulder, being presumably a slow progTess, would appear to 
present a different problem. 
* Of Van Calker, Zeits. Deutsch. Geol. Ges., vol. xli., p, 343 (1889). 
