Marcu 1, 1901.] 
CURRENT NOTES ON PHYSIOGRAPHY. 
THE CASCADE MOUNTAINS. 
THE Cascade mountains are genetically de- 
scribed by I. C. Russell (A Preliminary Paper 
on the Geology of the Cascade Mountains in 
Northern Washington, 20th Ann. Rep. U.S. 
Geol. Surv., 1900, pt. II., 83-210; 10 pl., 3 
maps) with such success as to give much support 
to rational or explanatory methods in place of 
the absolute or empirical methods that have long 
prevailed. Instead of being a sharp crested 
uplift, the mountains constitute a plateau, be- 
lieved to have been produced by the elevation 
of a peneplain, but now maturely dissected. 
The area described, from 100 to 150 miles wide 
east and west, and of greater but unknown 
length north and south, seems to have been 
once a nearly flat-topped dome, 7,500 to 8,000 
feet in altitude, composed of greatly disordered 
rock masses, whose tilted strata had been 
broadly truncated by long-continued erosion 
when the whole region stood lower. The uplift 
ofthe dome is given alate Tertiary date, because 
the sediments and lavas of the Columbia basin 
are tilted up along the eastern slopes of the 
elongated dome ; here landslides, to be counted 
not by hundreds but by thousands, have oc- 
curred along the escarpments formed by the 
resistant lava sheets overlying weaker sedi- 
ments. The granite mountains about Lake 
Chelan and the dissected volcano known as 
Glacier peak overtop their surroundings ; the 
former are thought to owe their height not so 
much to resistant structure as to local uplift in 
excess of their neighbors. (An alternative ex- 
planation is offered, but discarded, to the effect 
that the ancient peneplain lay at the level of the 
granite summits 2,000 or 3,000 feet above the 
present skyline.) It is explicitly stated that 
no remnants of the uplifted peneplain are to be 
seen to-day in the form of even uplands at 
mountain-top height; dissection has everywhere 
advanced so far as to leave only sharp ridges 
between deep valleys. The work of the glacial 
period is indicated in countless cirques or cor- 
ries, whose floors were so far widened that the 
spurs between them became sharply serrate ; by 
numerous trough-like main valleys, with hang- 
ing lateral valleys; by lakesand moraines. The 
depth to which certain valleys, like that of Lake 
SCIENCE. 
351 
Chelan, have been eroded is taken to prove that 
the region stood about 1,000 feet higher than 
now in preglacial time ; the capacity of glaciers 
to over-deepen their valleys not being accepted. 
THE GLACIER OF MT. ARAPAHOE. 
W. IT. Lee describes ‘The Glacier of Mt. 
Arapahoe, Colorado’ (Journ. Geol., VIII., 1900, 
647-654, 2 pl.) as occupying a cirque opening 
to the north beneath a summit whose altitude 
is 13,520 feet. The front of the ice shows a 
stratified structure, aud crevasses are believed 
to break its surface, while a moraine follows its 
front, and a stream, whitish with rock flour, 
issues from its base. The valley into which 
the cirque opens has a broad floor and pre- 
cipitous sides; it holds several small lakes, 
sometimes in rock basins, sometimes behind 
barriers of waste. Evidently the existing gla- 
cier isasmall affair compared with the ice stream 
that once stretched down the valley towards 
Boulder creek. 
RHINE, DANUBE AND NECKAR. 
THE depredations committed by the Rhine 
and its large branch, the Neckar, on the head- 
waters of the Danube, already somewhat studied 
are clearly 
by others, set forth by Penck 
Fia. 1. Headwaters of the Danube between those of 
the Rhine and the Neckar. B, Blumberg ; D, Donau- 
eschingen; R, Rottweil; 7, Tuttlingen; V, Vil- 
lingen. 
(Thalgeschichte der obersten Donau. Verein 
f. Geschichte des Bodensees u. s. Umgebung, 
1900?). He shows that several ancient conse- 
quent streams flowing down the eastern slopes 
of the Black forest.entered the Miocene sea of the 
