i'rit<'fi<i of hr'iff- — f jiJkiiii. 383 
]H'no(l than I should he alilc. i>n the Imsis of my ol»sci-vationsaii(l 
the foregoino- criteria, to adiDit. ThiMV wi-rc surely, as 1 think, 
extensive and thick deijosits of sul (glacial till. l»esides some 
scanty subglacial beds of stratified gravel, sand, and clay, and 
!the aggregate mass of the sidiglacial diift aijpears to me without 
doubt to exceed, and perliaps two oi- tluee times over, the mass 
•of the ice-held drift. 
'L;st!moHij of Exist Iikj Jn-slmts. Dr. X. (). Hoist in his ex- 
jiimination of portions of the margin of the (Jreenland ice-sheet, 
found extensive dejKjsits of both englacial :ind subglacial drift, 
respectively characterized l)y angular and l)y glaciated stones aud 
'boulders. The largest accumulation of snperglacial drift, which 
had been englacial. was observed on the southern edge of a lolte 
^)f the ice near Fredei-iksli;i:ili. The drift co\criug the ice surface 
Jiere extends along a distance of nearly twelve miles, and reaches 
a half mile to one and a half miles upon the ice. According to 
Hoist's Swedish r(>port of his observations, summarized in tiansla- 
tion by Dr. Josua Lindahl.'' the (juantity aud upper limit of the 
•snperglacial drift at this locality an- as follows: 
Its thickness is always greatest near laml, but here it is often (juite 
ditticult to estimate its actual thickness, as it sometimes forms a compact 
■covering, onl}^ in some fissures showing the underlying ice. This un- 
even thickness of the moraine-cover offers to the ice a proportional!}' 
vaiying protection against the sun. It thus happens tliat the une((ual 
thawing moulds the imderlying surface of the ice into valleys and 
hills, the latter sometimes rising to a liight of tift\' feet al>ove the ad- 
jacent valley, and l)eing so densely covered with moraine maierial tliat 
this completely hides the ice core, which, however, often forms the main 
part of the hill. 
Farther in on the ice, the moraine gradually thins out. At the local- 
ity just referred to, the moraine-cover, 3,000 feet from laud, measured 
■several inclies in depth: still tlie ice was seen in some bare spots. Be- 
yond 4,000 feet from land, the moraine formed no continuous cover, and 
at 8,:j00 feet it ceased entirely, with a perceptible limit against the clear 
ice. Onh' some scattered spots of sand and gravel were met with even 
a few hundred feet fartfier in on the ice. Dr. Hoist estimated tlie aver- 
age thickness of the moraine taken across its entire width near its east- 
ern end at one to two feet. The limit between the moraine-cover and 
the pure ice is always located at a considerable tliongli varying elevation 
above the edge of tlie inland ice. In the instance of the above-men- 
tioned moraine it varied between 200 feet and ."iOO feet. 
Terminal moraine ridges in i)r()cess of accumidatiou on the 
*Am. Naturalist vol. x.\il, pp. 589-598 and 705-71:?, July and Aug., 1888, 
