386 WILLIAM HERBERT HOBBS 
nourishment and waste in distribution with reference to altitude are 
thus not realized, and the otherwise universal law of exclusive 
drawing in of the foot of the glacier during its waning stages does 
not hold. 
That this is true is particularly well shown in the area of waning 
glaciers described as “‘ice-slabs” by Ferrar, the glacialist of the 
first Scott Expedition to the Antarctic, and fully mapped by 
Griffith-Taylor, Debenham, and Wright of the last Scott Expe- 
dition’ (Fig. 15). Ona far larger scale and related to a continental 
glacier rather than an ice cap, these dying glaciers represent a 
later stage than those marginal types which have already been 
referred to from West Antarctica—the Gourdon, Hobbs, and 
Rabot glaciers of James Ross Island. 
By examination of the map (Fig. 15) it will be noted that these 
glaciers must in an earlier stage have been connected together as a 
piedmont which was then a part of the parent area of inland ice 
lying to the westward. From that continental glacier when 
detachment occurred the rims of the battery of remodeled cirques 
which rise west of the existing glaciers must have emerged from 
the ice mantle in forms not unlike those now seen on the margins 
of James Ross Island. Their subsequent diminution in size has 
gone on through withdrawal both from the cirques and from the lower 
portions of their valleys—from both extremities toward a central 
position at a moderate altitude, where the last stand will be made before 
final extinction. 
The usual law of ablation regulated with respect to altitude 
here plays, therefore, no part, and it is evident that the reflection 
and consequent intensification of solar heat radiation in the neigh- 
borhood of exposed rock walls has here been the controlling factor 
in localizing the wasting process. This effect of exposed rock 
surfaces has been recognized for high latitudes by the observation 
of moats surrounding nunataks? and of the lateral streams beside 
glacier tongues? 
t Robert F. Scott, Scott’s Last Expedition, Vol. II, map opposite p. 198. 
2 “Characteristics of Existing Glaciers,” pp. 169, 257, Pl. 33B. 
3 [bid., Pl. 25A. 
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