332 A. E. BARLOW — LAURENTIAX AND HURONIAN ROCKS. 



rise to the Laurentian gneiss. The immense pressure exerted by the 

 weight of the superincumbent mass of Huronian strata and the crum- 

 pling, folding and fracturing of the comparatively thin and weak crust 

 would all tend to sink the lower portions of the Huronian beneath the 

 line of fusion, the submergence of which would produce conditions of 

 contact such as have been described and which subsequent upheaval 

 and denudation have exposed. 



