34 BULLETIN OF THE NATURAL HISTOKY SOCIETY. 



These limestones and shales are seen cropping out for two 

 miles at least further up river and underlie the gypsum. This 

 I have before described as exposed just above the mouth of the 

 Wapskehegan. It here forms a cliff not more than thirty or 

 forty feet high, but becomes much thicker at the main 

 Plaster Eock, which rises perpendicularly to from eighty to 

 one hundred and twenty-five feet. 



About one mile and a half back of the river at Plaster 

 Rock is the so-called Plaster- Rock Ridge, a long, level ridge 

 with rather steep ends and sides. It stands considerably 

 higher than the '' rock," and is prominent in the view from far 

 down the river. It is composed, according to Dr. L. W. Bailey, 

 of conglomerate, forming the highest member of the Lower 

 Carboniferous series of Victoria County. Between this ridge 

 and Plaster Rock are numerous sink holes, caused by the 

 solvent action of water on the gypsum beneath. Two mineral 

 streams join the river near the rock, they are weak solutions 

 of Epsom or some such salt. 



About two miles further up river I noticed red cliffs, 

 probably of red sandstone. My remarks on the geology of 

 the district beyond this point are borrowed, chiefly from 

 reports by Dr. Bailey and Mr. R. Chalmers, of the Geological 

 Survey. 



Trap rocks usually occur with the first and last beds of 

 the Lower Carboniferous. On the Tobique they have been 

 noticed near the ends of the basin, on the Otelloch Brook at 

 Red-Rapids Bridge, and at Blue Mountain, which is at the 

 northern limit of the formation. They are supposed to be 

 contemporaneous with the newer and higher beds of the 

 series. 



Beyond the carboniferous basin the river and its tributaries 

 run through a Silurian area, the northern and western branches 

 passing only through this formation, while the southern and 

 eastern branches rise among older formations in highlands 

 which form the watershed between the Miramichi and 

 Nepisiguit. At the head of the Wapskehegan and Gulquac 

 rivers rocks of the Ordovician System appear, as well as ort 



