DEVELOPMENTS IN PRE-CAMBRIAN STRATIGRAPHY 387 
Keewatin, which included the surface rocks, composed largely of 
volcanic flows, and (2) the Laurentian, consisting largely of plutonic 
granite and gneiss. During the last few years, however, has it 
been found that the so-called Keewatin complex includes a much 
larger proportion of sedimentary rocks—conglomerate, arkose, 
greywacke, slate, etc.—than was formerly supposed, and to these 
various local names—Pontiac schist," Fabre Series,? Timiskaming 
Series,? Sudbury Series, etc.—have been given. These rocks have 
been found in almost every area where detailed geological work 
has been carried on. They occur in the Sudbury district, in the 
vicinity of Lake Timagami, in the Larder Lake district, in the 
Cobalt region, in the Porcupine district and in numerous localities 
in northwestern Quebec. In the last-mentioned region a belt of 
fine-grained, rusty mica schist, which contains squeezed pebbles 
of granite and greenstone, has been traced continuously for roo 
miles by J. A. Bancroft and the writer. Throughout all this dis- 
tance the schist is intruded by dikes of granite, aplite, and peg- 
matite, showing conclusively that it is older than at least part of 
the Laurentian gneissic complex. In defining the various series 
to which these rocks have been referred, it has been assumed in 
most cases, (1) that they belong to the Huronian, and (2) that they 
are younger than all the volcanics of the basement complex. 
Both of these assumptions are probably unwarranted. In 
objection to the use of the name Huronian for the sediments 
occurring in the volcanic complex, it might be pointed out that 
they occur throughout an area of many thousand square miles, 
and everywhere possess characteristics which are distinctly at 
variance with those of the typical Huronian. They form a part 
of a basement complex which, as shall be shown later, probably 
_ lies stratigraphically below the original Huronian. Lithologically 
they have little in common with the original Huronian, and unlike 
the Huronian, they are everywhere highly folded, foliated, and 
intruded by granite batholiths. The second of these assumptions 
implies that the sedimentary rocks are stratigraphically as well as 
lithologically separate from the volcanics, a conclusion which is con- 
1M. E. Wilson, Sum. Rep. Geo. Surv. Dept. of Mines, Can., p. 175, 1909. 
?R. Harvie, Geology of a Portion of Fabre Township (Dept. of Mines, Que.), 1911. 
3.W.G. Miller, Eng. and Min. Jour., XCII, p. 648, tort. 
