312 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
the canon-bottom, (5) excavate rock-basins, (6) develop cirques, 
and, in general, transform such canon into an equally typical glacial 
canon ” (’ 83 , 238). A later paper by the same author is referred 
to below. 
Hanging Valleys in the Alps .— Valleys that are here called 
“ hanging ” have frequently been described by observers in the Alps, 
but either without particular reference to their discordant relation to 
the main valleys, or with acceptance of normal erosion in the main 
valley as the cause of their discordance. Rtltimeyer’s and Heim’s 
views on discordant lateral valleys have been already referred to. 
An account of the Salzachthal in the Tvrol, bv Bruckner, describes 
it as one valley in the bottom of another; the deeper one being 
relatively narrow and steep-sided, while the sides of the higher 
valley Hare wide open; the side streams are described as falling into 
the deeper main valley; but this significant feature is not mentioned 
as if it were of general occurrence, nor is it explained by glacial 
erosion (’ 85 , 95). 
Lubbock, in his “ Scenery of Switzerland,” follows Rutimeyer 
and Heim. After statins; that the side valleys of the Reuss have a 
moderate grade wliich brings them out at the level of one of the ter¬ 
races or Thalstufen of the main valley, from which their streams cas¬ 
cade down into the main stream, Lubbock writes : “ It is obvious that 
this terrace represents a former 4 Thalweg ’ of the Reuss with much 
less fall than it has now, and that the river has deepened its valley 
more rapidly than the lateral streams, so that these glens open at 
some distance up the side of the valley, and their waters join the 
Reuss by rapids or waterfalls.The valley shows clear evidence 
of glacial action. The hard rocks are in places quite polished. This 
is especially the case with the buttresses which stand like doorposts 
where the lateral glens open into the main valley, and particularly 
on the right side of the eastern glens, the left of the western, where 
of course the pressure of the ice was greatest ” (’ 96 , 332, 334). 
Russell on Hanging Valleys , 1887. — Russell gave a detailed 
account of what may be called hanging valleys in his report on the 
Quaternary History of Mono Valley, California. In a section on 
“high lateral canons,” he says: “In a number of instances in the 
Mono basin the low-grade glaciated canons receive branching canons 
at a considerable elevation above their bottoms, the branches also 
having a low grade. This is illustrated where Lake Canon opens 
into Lundy Canon. Each of these gorges has an approximately 
horizontal bottom near the place of union, but the former is a thou- 
