200 THE ANTARCTIC MANUAL. 
clearly recorded, and the relation between the height to which either 
the surface of the ice or material transported on or in it has been 
pushed up, and that from which the mass to which the thrust is due 
has descended, should be carefully observed. 
(9) Ground Moraine.—Where glaciers can be observed resting 
directly on the ground, the lower layers will probably be found 
crowded with mud, pebbles and boulders. Note whether there is 
any layer of such material dragged forward by the movement of the 
ice above; and whether there is a gradual, imperceptible passage 
from frozen mud below the glacier into ice crowded with detritus, 
and from this again to ice with bands of detritus and thence to 
comparatively pure ice. Also how far such material can accumulate 
so as to form a cushion of any thickness between the lowest layer of 
ice, whether clean or dirty, and the live rock, and the circumstances 
under which such accumulation, if any, occurs. 
(10) Boulder Clay—Any signs of stratification in a boulder clay 
or till should be carefully noted, and any inter-bedding of this with 
sands or gravel. Such material, and especially the former, should 
be carefully searched for organic remains, and the mode in which 
these occur should be noted, whether broken or whole, or in positions 
of growth. Samples also of the clay should be secured, that they 
may be searched for ostracoda, foraminifera, etc. The included rock- 
fragments should be carefully studied, and the locality from which 
they have heen derived should, if possible, be ascertained. Great 
attention should also be paid to their form, whether angular, sub- 
angular, or rounded; in other words, whether fragments obviously 
water-worn or the reverse are abundant or preponderant. 
(11) Evidence as to whether the ice in Antarctic regions is 
now at its maximum extent, or whether it has anywhere retreated, 
should be carefully sought. Thus, wherever the ice does not actually 
come down to or beyond the sea margin, such indications of its former 
presence as rounded and striated rocks, perched blocks and moraines, 
should be recorded, and where any large mass of rock is visible, this 
should be carefully examined for inter-stratified boulder beds, in order 
to see whether there is evidence that the region has passed through 
more than one glacial age. 
Two forms of deposited material, directly or indirectly associated 
with land ice, are still very imperfectly understood. One consists of 
the peculiar mounds of sand, gravel and rock fragments called Eskers, 
Asar, or Kames. These sometimes bear a general resemblance to 
moraines, at others are more like rude and magnified copies of rather 
