124 '' ^1 lOIINSTON MEMORIAL LKCTUUK. 



of diabase. These are rotted, throuj>h weathering-, to a depth 

 of from laeth to 1 10th of an inch. The writer thinks it 

 would take over 1,000 years for diabase to weather to this 

 extent. Many of the "cores" show discoloration due to the 

 action of fire, which was evidently used to cause the pebbles 

 to exfoliate in curved flakes. 



More search in this area is much to be desired, as it 

 mipht reveal an early stage in the evolution of the fashion- 

 ing of stone implements by the Tasmanian aborigines. Only 

 one implement fomied of chert was found, among the 100 

 collected, at Regatta Point. 



i.e. At Lake Leake last February the writer found ovev 

 100 specimens of stone implements of the Tasmanian 

 aborigines in what appears to be the beach of an old lake 

 before it became naturally drained. The site of the old 

 lake has now been used as a reservoir so that the water 

 level, as the result of the damming cf the valley forming 

 the present outlet of the reservoir, has now risen about 10 

 feet, to that of the small teirace where the implements were 

 found. The writer takes this slight terrace to be a relic 

 of an old shore line. It may be mentioned that under two 

 miles to the south-east there is an aboriginal stone quarry, 

 where large numbers of these implements were fashioned, 

 all made from cherts. These cherts were formed by the 

 alteration of Jurassic clay shales along their plane of con- 

 tact with masses of intrusive diabase. The author would 

 not press for this last piece of evidence proving any special 

 geological antiquity for the "tronattas," but thinks it should 

 be recorded, as the area is worthy of further investigation. 

 Evidence i.b. conclusively proves geological antiquity to be 

 something of the order of perhaps 1,500 years, for within 

 the last 100 years no appreciable alteration has been ob- 

 served in sea-level anywhere around the shores of Australia 

 or Tasmania. i.a. can prove a far higher geological an- 

 tiquity for man if the "outwash" api'on material dates bad. 

 to the Riss Pleistocene ice sheet. The locking up of so much 

 ice to form the great Riss ice sheets might have lowered 

 .sea level all over the world to the extent of about 200 feet. 

 The levels of the old valley gravels at the Tamar and Mersey 

 Rivers, together with the submerged terraces at about Sis 

 fathoms to the west of King Island, point to the sea level 

 having been lowered In late geological time to the extent 

 of about 200 feet, and to have paused long enough at this 

 low level to enable it to cut back a terrace over 50 feet in 



