76 THE GLACIER EPOCH OF AUSTRALASIA. 
load of foreign matter as it melts, as in the terminal and 
lateral moraines, and perched blocks, at the foot or in slopes 
of mountain valleys, or in the erratics dropped in the soft bed 
of lakes, estuaries, or seas, from the melting or overturning 
of ice sheets or icebergs. 
The character of these evidences is in no way affected by 
considerations as to the primary cause of the lowered tem- 
perature, which will be discussed hereafter on its own merits, ° 
The evidences, therefore, upon which we must rely, mainly, 
as proof for inferring the occurrence of a glacial epoch im 
Australia and Tasmania, may be summarised as follows :— 
Evidences of former Glacial Action. 
1. Terminat MoRAINEsS. 
The existence at or near the mouth of the fan-shaped 
openings of narrow mountain valleys, of mounds, sometimes 
of great extent, of loose tumbled materials, forming hetero- 
genous masses of rock boulders, shingle, gravel, and other 
detritus, showing no signs of arrangement in layers or 
bedding as in detrital distributed by water. The harder 
rocks are often polished and worn on one side, and frequently 
exhibit, more or less distinctly, fine lines, scratches, or 
grooves, which usually run along the surface parallel to the 
greater axis. Some of the blocks may be many tons in 
weight. These moraines are evidence of the detritus left at 
the melting extremity ofa glacier, or mark the line of its 
final retreat. 
2. Laterat MorAInESsS AND PERCHED BLOCKS. 
Similar materials found fringing the sides of the higher 
slopes of a mountain valley, especially large masses of rock 
(perched blocks), differing in character from the rock slopes 
or crown above them, may indicate the retreat of a diminish- 
ing glacier; but as the greater part of these accumulations 
often fall eventually to a lower level by gravitation, it would 
be difficult to distinguish these from accumulations gravitating 
from higher slopes ia the ordinary way. Large foreign 
erratics, and polished and striated stones, alone can be 
depended upon where such intermixture is possible, as at the 
foot of all steep mountain slopes. 
8. RocuEes-Movutronnrzes, AND Icze Scoorep Lake Basins 
OR Tarns. 
In certain parts of valleys in which the detritus of glaciers 
occur, the river of ice of great weight, and shod with hardened 
rocky materials, exerts immense pressure and wears down, 
polishes, and rounds off the surfaces and edges of such 
