12 
MUSEUM BULLETIN HO. 24 
south of the Strait of Belle Isle. 1 * * Portlandia artica "now only 
lives in sea water at a temperature below 0 degrees Centigrade 
and thrives in the muddy waters discharged at the mouth of 
glacier streams.” 4 The silty lower clays holding Portlandia 
artica and other fossil shells of arctic species occur in the vicinity 
of Ottawa at altitudes from 130 feet in the lowest portion of the 
Ottawa valley up to at least 510 feet above sea-level, the highest 
locality, so far as known, being at the above-mentioned locality 
near Kingsmere. Portlandia artica also occurs in the sandy 
beds in the upper portion of the lower clay, as well as many of the 
other species ; but the forms are generally small as compared with 
those of the lower portion, apparently showing an amelioration 
of temperature conditions. The fauna occurs in the lower clays 
most abundantly at altitudes from 175 feet up to 275 feet above 
sea-level. 
The upper clays are generally nearly barren of fossil shells. 
This is especially the case in their upper portion. In the sandy 
layers interbedded with clay layers near the base of the upper 
clays, Macoma Balthica Lin. sometimes occurs in considerable 
numbers. Saxicava rugosa also occurs and, rarely, small forms 
of Portlandia. In general, though, the abundant and character- 
istic fauna of Arctic species found in the lower clays is absent in 
the upper clays. 
As the typical and common species of the lower clays have 
been found to live abundantly in high arctic seas only at depths 
of from about 10 to 30 metres, 8 and as these clays in the vicinity 
of Ottawa occur at altitudes of from 130 feet up to at least 510 feet 
and occur abundantly at altitudes from 175 feet up to 275 feet 
above the sea, hence it is evident that the sea must have stood at 
a considerably lower level with respect to the land when the lower 
clays holding shells of arctic species were deposited in the lowest 
part of the Ottawa valley than when those at high altitudes were 
deposited. The clays at low altitudes could not have been 
deposited during the time of emergence of the land for they are 
i Whiteavea, J. F., “Catalogue of the marine invertebrata of eastern Canada.” Geol. Surv., 
Can., 1901, p. 127. 
* Wright, W. B., "The Quaternary Ice Age,” p. 327. 
* BrOgger, W. C„ Ibid, p. 681. 
