34 NOTES ON MT. ANNE AND THE WELD KIVKU VALLEY. 



ing effect of the Riss glaciers have left almost contrary 

 results on our glacial topography. 



Following this and clearly superimposed on it come the 

 relics from the Wiirm glaciation, typified by the mountain 

 tarn. The period of glaciation was this time far less intense 

 than during the Riss period. Only the tops of the more 

 elevated mountains were affected, and the nivation line 

 appears to have rested at an elevation of about 4,000 feet at 

 Cradle Mountain, as evidenced by Lake Wilks, and similarly 

 in the National Park and Mt. Anne, as shown by the 

 elevated tarns at about that height. The duration was only 

 sufficient for very small cirques and rock-scooped basins to 

 l)e formed. Small hanging or cliff glacierets and horseshoe 

 glaciers grew, but did not travel far or obscure the evidence 

 i)f the Riss glaciation. One of the best specimens of a 

 moraine the writer has seen, however, lies to the east of 

 Lake Newdigate in the National Park, and is attributable 

 to this period. The distinguishing feature of the Wiirm 

 glaciation may be said to be the mountain tarn. 



A point that warrants passing note here and needs 

 further investigation is the effect of one of these periods of 

 glaciation on the edge of our higher mountains. At about 

 .'^,500 feet round the mountains of the centre, south, and 

 north-east of Tasmania run lines of cliffs. The regularity 

 with which these occur suggests that during one of these ice 

 periods, probably the Wiirm, the nivation layer in the atmo- 

 sphere rested at this height round the contour of the moun- 

 tains, and here the intense frost action carved out the lines 

 of cliffs so common near the tops of our mountains, such as 

 the "Organ Pipes" on Mt. Wellington, the Bluffs of Ben 

 Lomond, and the cliffs in which the northern face of the 

 Western Tiers culminates. The concave shape of many high 

 nwuntain peaks, Mt. Ida and Wyld's Crag for example, may 

 be due to the fact that they protruded their summits into 

 this nivation layer, which has worn a circlet of cliffs round 

 the peak. These cliffs formed the starting point of an 

 ice flow, resi'mbling a ollar round the mountain, which 

 descended the slope for some distance before melting. There 

 is ample evidence on Mt. Wellington and on the track to 

 Lake F^enton under Mt. Field East of accumulations of rocks 

 resembling moraines and almost certainly ice borne. At 

 least many of them could not have rolled into their present 

 position, and it is clear that they reached their present 

 pssition before the present vegetation grew up. 



