THE GABBRO LAKE PLATE OF THE MESABI IRON RANGE, 1899. U. S. GRANT. 



of primary jaspilyte, one igneous and one sedimentary. These belong in the Lower 

 Keewatin, as a rule; but in the basal conglomerate of the Upper Keewatin is found 

 a secondary orfragmental jaspilyte, consisting of detritus from the original jaspilyte 

 of the Lower Keewatin. This is common on the " south ridge " at Tower. It is 

 sometimes very coarse, but also grades into grit and graywacke. N. H. w. 



