HY A. N. LKWIK. M.C.. LL.B. 33 



reach the bottom to coalesce with ice from neighbouring hills; 

 for example, the Florentine Valley formed a gap of several 

 miles between the ice cap of Mt. Field and the ice in the 

 Vale of Rasselas. On these mountains the ice moved for 

 some distance down the pre-glacial valleys, leaving its im- 

 print on the topography. During this invasion the ice cap 

 spread far out over the central plateau, being responsible for 

 the many lakes and tarns between Cradle Mountain and the 

 Ouse, and most probably responsible directly, or indirectly 

 through the action of the intense cold on the rocks of the 

 plateau, for the origin of the basins in which the Great 

 Lake, Lake Echo, and Lake Sorell lie. It is possible that 

 these are rock basins scooped by the ice sheet, but there is at 

 present no direct evidence to couple their origin with ice 

 action. The small glaciated areas on Mt. Wellington and 

 Ben Lomond possibly belong to this period, and there are 

 indications that many of the mineral-bearing drifts of the 

 north-eastern highlands are glacial outwash fans. The 

 characteristic remains of the possible Mindel glaciation in 

 Tasmania are the broad flat plains throughout the western 

 parts that are generally known as buttongrass plains. 



At present we do not know anything about interglacial 

 epochs, but following this period came the invasion by the 

 Riss glacial epoch. Conditions were far less severe than 

 during the Mindel times. The more elevated regions only 

 were affected. Valley glaciers of the Dendritic type (Hobbs, 

 1910) grew from neves on the ranges and crept a short 

 distance down the mountain valleys. These glaciers are 

 responsible for the great cirques that contribute so much to 

 our finest mountain scenery. As a rule the glaciers did 

 not debouch far from their mountain valleys. They spread 

 great deposits of moraines over the plains surrounding the 

 valley mouths and for some distance up the valleys them- 

 selves, where morainal banks frequently dam back fine shec'ts 

 of water. Between the cirques and U-shaped glacial valley.s 

 there still remains much of the older surface showing the 

 rounding effects of the older Mindel ice cap. The glaciers 

 occurred during this period on all mountain ranges in the 

 western half <;f Tasmania over an elevation of 3,000 feet, and 

 near the coast evidently reached much closer to sea level. 

 The cirques and moraines of Lake Judd, Lake Seal in the 

 National Park, Lake Dove in Cradle Mountain, and all the 

 more striking signs of glacial action belong to this Risa 

 period, which may bo termed the cirque-forming period. The 

 rounding effect of the Mindel ice sheet and the cirque-form 



