No. 5.] HIND — NORTH-EASTERN LABRADOR. 263 



able, and the strata present themselves in enormous anticlinal 

 and synclinal folds, which are easily traced, in some instances 

 over half a quadrant. In numerous examples, too, the dips 

 were found to be low, varying from 15 to 45 degrees, and the 

 prevalence of low dips was noticed at localities a hundred miles 

 apart, as for instance in Porcupine Bay, near to Sandwich Bay, 

 and in Lake Melville at the head of Hamilton Inlet. At Esqui- 

 mo Island, close to the mouth of the Narrows above Rigoulette, 

 the dip was from 20 to 25 degrees, and in the vicinity of English 

 River, for long distances, about 25 to 30 degrees. In the neigh- 

 bourhood of trap intrusions the strata are necessarily disturbed, 

 but as these intrusions appear to follow certain well defined 

 lines, the undisturbed portious of the Lower Laurentian in and 

 about Hamilton Inlet and Lake Melville, show a regular and 

 symmetrical folding. 



II. — Concretionary Structure. 



When the ice-planed surfaces of those beds which present a 

 dip more nearly approaching the vertical, are carefully examined, 

 the observer is very liable to be misled, unless he follows out the 

 apparent undulations which may arrest his attention. These 

 are frequently found to be due to a concretionary structure on 

 a grand scale. Small and thin lenticular beds of micaceous 

 schist, for instance, are seen to be followed regularly by larger 

 zones of the same rock, and the impression is conveyed that 

 many of the supposed minor undulations are merely part of great 

 concretionary forms. 



The tendency to a lamellar arrangement of thin sheets about 

 a nucleus, highly compressed and drawn out, is oftentimes very 

 marked and very deceptive ; it was observed in several cases to 

 extend over more than a hundred yards in length, without a 

 break, and probably the concretionary structure involves very 

 much larger masses, and may not unfrequently give rise to ap- 

 parent instances of supposed folding. 



III. — Boulders and Outliers of the Upper Laurentian 

 or Labrador Series. 



Boulders of Labradorite and occasionally of Hypersthene, are 

 of common occurrence all the way from Porcupine Bay to the 

 head of Lake Melville (140 miles), in a south-westerly course. 



