Mr. McConnell described these deposits as resting on the limestone and well exposed in high cliffs on both sides of Athabaska river. At Cascade rapid, this formation is one hundred and fifty feet thick and is so saturated that pure tar oozes out of the bank in several places and streams down the slope. Mr. McConnell proceeds in his report to say:—“The tar-sands mentioned above belong to the Dakota formation and constitute in this region the basal member of the Cretaceous system. They rest unconformably on the Devonian limestones. Lithologically they may be described as soft sandstone, the cementing material of which is a bitumen or inspissated petroleum derived from the underlying limestones. The sands are siliceous and usually rather fine-grained, but also grade occasionally into a coherent grit. The eastern boundary of the tar-sands was not precisely defined, but their outcrop was estimated to have a minimum distribution of fully one thousand square miles. In thickness they vary from one hundred and fifty to two hundred and twenty-five feet. The tar is unequally distributed through the sands, in some places merely staining the grains, but in most of the sections examined it is present in sufficient quantity to render the whole mass more or less plastic. An analysis by Mr. Hoffmann of a specimen collected some years ago by Doctor Bell gave by weight:— Bitumen 12·42 per cent. Water (mechanically mixed) 5·85 per cent. Siliceous sands 81·73 per cent. A cubic foot of the bituminous sand rock weighs, according to Mr. Hoffmann, 117·5 lbs. This figure multiplied by the percentage of bitumen, 12·42, gives 14·59 lbs. as the amount of bitumen present in a cubic foot, or 14·59/63·7 = 22·9 per cent. in bulk, taking 63·7 pounds as the weight of one cubic foot of rock. At the minimum thickness of one hundred and fifty feet, and assuming the thickness as given above at one thousand square miles, the bituminous sand rock in sight amounts to 28·40 cubic miles. Of this mass, if the preceding analysis is taken as an average, although this is probably rather high, 22·9 per cent. in bulk or 6·50 cubic miles is bitumen. This calculation can, of course, only be regarded as an approximation, but will serve to give some idea of the enormous outpouring of bituminous substances which have taken place in this region. The amount of petroleum which must have issued from the underlying limestones required to produce 6·50 cubic miles of bitumen cannot be estimated, as the conditions of oxidation and the original composition of the oil are unknown. It must, however, have been much greater than the amount of bitumen.