Personal and ScientHic News. 119 
Alaska." He described the formation of the tundra and remarked the 
absence of residual clays, and other evidences of rock decay, as also 
the absence of glacial records along the Yukon and Porcupine rivers. 
No evidences of glaciation exist between the Yukon and the Arctic 
ocean. From the head waters of the Yukon the movement <A glaciers 
has been northward and southward. Incidentally he made a striking 
suggestion that the gneat mo-<sy tundra if inundated would on the dis- 
solution of its ice, leave a thick vegetable deposit comparable with a 
bed of coal. Discussed by Shaler, Chamberlin, Newberry and Lawson. 
State geologist, p]d ward Orton, read a paper on the "Origin of the 
rock-pressure of Natuial Gas in the Tienton limestone of Ohio and In- 
diana." He showed that the pressm-e decreases westward, and adduc- 
ed convincing facts supporting the theory of hjn'ostatic origin. The 
facts show the |)i-e8sure to be directly proportional to the depression 
of the oil and gas bearing stratum beneath t)ie level of lake Superior. 
Adverting to the question of duration of the gas supply, he expressed 
the positive conviction that it is destined to last liut few years. The 
paper was discussed by I. C. "White, Lawson and ]\[cGee. 
Professor "W. B. Clark read a paper "On the Tertiary Deposits of the 
Cape Fear river region." The post-Cretaceous erosion left an irregu- 
lar surface over which the older Tertiary deposits were spread. Post- 
Eocene erosion approximately base-leveled this surface, leaving the 
early lertiary sediments jireserved in the deeper post-Cretaceoiis de- 
pressions. Upon this surface the Miocene strata were laid down. 
From this history has resulted an intermingling of Cretsceons and 
Eocene forms in several places, and even of Cretaceous and Miocene 
types. 
Dr. A. C. Lawson, of Canada, read a "Note on the pre-PahTozoic 
surface of the Archaean terranes of Canada." He showed that along 
the northern limit of the pahTe'>zoic rocks the surface of the Archaean 
was, at the time of the deposition of the Cambrian, or earlier forma- 
tions, to a large extent, as hummocky and worn as it is to-day. Hence 
the feature known as roches montonues cannot, as is generally supposed 
be due to conditions of the gl.Mcia) epoch, except to a very limited 
extent. There has been but slight reduction of the Archrean surface 
since early paheozoic time ; but the previous denudation was enormous. 
Discussed by Dr. Spencer. 
Mr. K. G. ]\IcCoiinell, of Canada, described the "Glacial features of 
parts of the Yukon and Mackenzie basins." Kead by J. B. Tyrrell of 
Canada. The i^aper embraced notes on the silting up of a southern arm 
of Great Slave lake, on the hight of erratics along the eastern flanks 
of the Rocky mountains, on the absence of bowlder-clay from the val- 
leys of the Porcupine and the Yukon, and on the former existence of a 
great lake at the confluence of these two streams. Discussed by Davis, 
Russell and Gilbert. 
Mr. J. P>. Tyrrell read amomoir on "Post-Tertiary deposits of Manito- 
ba and .'uljoining territories of Canada." The area between the Ar- 
cha3an nucleus in eastern Manitoba and the font of the Hocky moun- 
tains, has had in preglacial times, a very irregular surface. This was 
planed bv the continental glaciers — the irregularities being often filled 
to great depth with the unstratified till. The till or ground moraine, 
occupies the surface over large districts, but. is covered in many places 
by stratified sands, silts and gravels deposited in the beds of larger or 
smaller fresh-water lakes. The author presented evidences of a recur- 
rence of glacial conditions ; and gave the i)ositions of a number of lakes 
in which the su]).sequent glacial de[)Osits were laid down. Discussed 
by Chamberlin, Shaler, McGee, Spencer and Tyrrell. 
A communi(!ation by i)rofessor G. F. Wright was read in abstract, in 
the author's absence, by professor C. II. Hitchcock. It was entitled 
