Oil the Norian or "Upper Laurentian" Formation. 431 



may perhaps occur elsewhere in the Laurentian, but Dr. 

 Bell, Mr. Low, 1 and Mr. Tyrrell, who have been chiefly 

 engaged in its exploration, consider it to be very impro- 

 bable that any other considerable undiscovered area should 

 still exist in the interior of the great Laurentian continent. 

 The courses of the large rivers which flow from the east 

 and from the west into the southern half of the Hudson 

 Bay, have been explored, but no trace of these rocks have 

 been found. Dr. G. M. Dawson also informs me, that in 

 carefully going over the whole literature concerning the 

 arctic regions of Canada, when constructing his geological 

 map of the northern part of the Dominion of Canada, he 

 could find no mention of rocks of this character. We 

 may, however, expect that similar occurrences will be 

 found on the south-west limit of the protaxis between 

 Lake Superior and -the Arctic Sea; but up to the present 

 time none have been discovered. It is, however, quite 

 possible that they may exist, covered by the palaeozoic 

 strata ; for strata of Silurian and Devonian age extend 

 along the side of the protaxis, and the underlying Cam- 

 brian rocks which would indicate more exactly the border 

 of the old continent are here, if they exist at all, overlaid 

 and concealed by these more recent deposits. 



VI. THE OCCURRENCE OF SIMILAR ANORTHOSITES 

 IN OTHER COUNTRIES. 



The largest developments of anorthosite with which we 

 are acquainted outside of Canada is probably found in 

 Norway. The rock called by the Norwegian geologists 

 Labrador rock, as well as some of Esmark's norites and 

 many of the so-called gabbros, are anorthosites. 



These rocks have been described by Kjerulf, 2 Reusch, 3 

 and others. They form enormous mountain masses, and 



1 Report of tne Geological Survey of Canada, Part R., 1836. 



2 Kjernulf, Die Geologie des sudl. und mittleren Norwegen, p. 261, ff. 



3 Reusch, Die fossilien fuhrenden krystall. Schiefer von Bergen, p. 84 ff. 



