386 Rk. BELL—HUDSON BAY MAMMOTH AND MASTODON REMAINS. 
one foot thick of irregularly mingled clay and spots of impure lignite. Next below 
this are 40 feet of unstratified drift, full of small pebbles, under which are a few 
feet of stratified yellowish sand and gravel. Resting upon the lignite are five feet 
of hard lead-colored clay, with seams and spots of a yellow color and layers of 
red, gray, drab, and buff. Above all and forming the top of the bank, 65 feet high, 
are 10 feet of hard drab clay, with striated pebbles and small boulders and holding 
rather large valves of Suxicava rugosa, Mucoma calcarea ( Tellina proxima), and Mya 
truncata. Small seams of lignite were seen in two places in the bank on the same 
side at and again half a mile below the foot of a rapid which occurs about six miles 
above the Opazatika. 
‘“Tn the interval between one and two miles above this stream the whole bed of 
the river appears to be underlaid by lignite. When sounded with a heavy pole, it 
has an elastic feel and gives off large volumes of gas, which may also be seen at any 
time bubbling up spontaneously here and“tirere all along this part of the river. 
This phenomenon has been observed by the Indians from time immemorial, and 
the locality has received the name of ‘The Bubbling Water.’” * 
At the foot of the long portage on Missinaibi river, which is four and 
a half miles within the Archean border, or that distance south of Round 
bay, at the head of the long southwestward stretch above described, 
there is a considerable thickness of fine silt in thin layers, with moss and 
remains of fresh-water marsh plants between most of them. The mean 
height of the deposit is about 90 feet above the level of the highest. oc- 
currence of the marine shells before mentioned, or probably about 550 
feet above the sea. At the time of the postglacial submergence this de- 
posit may have been forming at what was then the mouth of the Mis- 
sinaibi river, while the whole of the Paleozoic plain between it and James 
bay was covered by the sea. ; 
The deposits which have been described cover a very extensive dis- 
trict, namely, the low country embraced by a semicircular curve in the 
great Archean plateau, extending 200 miles southwest from James bay. 
This tract is all underlaid by the nearly horizontal Silurian and Devo- 
nian strata already mentioned. These rocks also appear to form the 
floor of the bay itself, which is 300 miles long and 150 miles wide. 
The lignite beds above described probably all belong to basins of lim- 
ited extent. The one which has been referred to as occurring in the 
bottom of a drift-filled valley which had been excavated in older till on 
the Kenogami river, and also most of the beds along the Missinaibi, are 
of interglacial age. The seam which has been mentioned as lying be- 
neath a thick stratum of till on Coal brook may be of preglacial age, in 
which case the blue clay below it would also be preglacial. Some of the 
higher beds of impure lignite further down the Missinaibi may be post- 
* Geological Survey Report for 1877-78, p, 4 C. 
