212 CBUISE OF THE NEPTUNE 



Islands of Group II. 



The only known occurrence of Silurian limestone on the 

 eastern side of Baffin island is at Silliman's Fossil Mount, near 

 the head of Frobisher bay, where the limestone forms a hill 

 1,000 yards long and 350 feet high, resting almost flat upon 

 the crystalline rocks. Seventy-two species were identified by 

 Schuchert from fossils brought back from this locality; he 

 refers them all to the Galena-Trenton. 



Little is known of the limestone about the great lakes, 

 Nettilling and Amadjuak, in the interior of Baffin, beyond the 

 meagre observations of Boas, who briefly refers to the limestone 

 about BTettilling and along the east side of Fox channel. These 

 limestones are probably an eastern extension of the Southamp- 

 ton area, but their exact age will remain unknown until fossils 

 have been collected from them. 



On the east side of Prince Regent inlet the rocks composing 

 the high cliffs of Baffin island are the basal sandstone and shale 

 overlaid by limestones, which in places are interbedded with 

 beds of gypsum. These high cliffs of limestone extend eastward 

 along the south shore of Lancaster sound to the mouth of 

 Admiralty inlet, when they give place to the Archaean crystal- 

 line rocks, which rise slowly to the eastward from beneath the 

 level of the sea, in a manner similar to that already described, 

 on the north side of Lancaster sound. 



Islands of Group III. 



The large islands of this group are mainly built of Silurian 

 limestones. North Somerset was the only island of this group 

 visited in the Neptune, and all information concerning the 

 others is derived from the observations made on earlier expedi- 

 tions, and contained in Dawson's summary of the northern 

 geology. 



