88 
president’s ADDRESS — SECTION C. 
them showing distinct marks of glaciation, and many of them having 
a coating of peroxide of manganese on that part which had projected 
above the mud when lying at the bottom. The rocks belonged to 
the following lithological types: — Granitites, quartz if ero us diorites, 
schistoid diorites, amphibolites, mica-schists, grained quartzites, and 
partially decomposed earthy shales. 
“ From the foregoing description it appears that the deposits 
forming at the most southerly points reached by the ‘ Challenger’ 
are composed chiefly of continental debris carried into the ocean by 
the (loati ng ice of those regions, and that this material makes up less 
and less of the deposit as the distance from the Antarctic Circle 
increases until it completely vanishes about lat. 4(1° or 47° S. The 
deposits along the Antarctic Ice Barrier, which hare been called blue 
muds, resemble in many respects the deposits formed at similar depths 
off the Atlantic coast of British North America. The nature of the 
rock fragments dredged in these latitudes conclusively proves the 
existence of continental land, probably of considerable extent within 
the Antarctic Circle. One of the fragments of gneiss dredged from a 
depth of 1,950 fathoms measured 50 by 40 centimetres, and weighed 
more than 20 kilogrammes.” 
This evidence proves that boulder-hearing clays and sands are 
at present being deposited on the ocean floor by the agency of ice- 
bergs, probably at least as far equatorwards as lat. 46° 8., over an area 
probably at least as large as that of Africa. By a change of ocean 
currents erratics might be carried on icebergs under present climatic 
conditions anywhere in the southern hemisphere where icebergs 
could float, to within 38°, or possibly even 35°, 8. lat. "Whereas, how- 
ever, south of lat. 46° S. the glacial deposits probably predominate 
over the radiolarian and diatom aceous earths, &c., north of that 
latitude to 35° 8. true pelagic deposits, such as red clays and 
foraminiferal ooze, would probably predominate over the glacial. 
(5.) Summary of Evidence. 
(1.) If possible traces of ice-action in the Siluro-Devonian 
conglomerates of Temora, in New South Wales, he omitted, there 
still remains conclusive evidence to show that there have been at least 
two distinct periods when ice was much in evidence in Australia and 
Tasmania. The first period commenced in Permo-Carboniferous time, 
and was perhaps prolonged intoTriassic time; the second was Pliocene 
or Post- Pliocene. 
(2.) By far the most extensive traces of glaciation in Australia 
and Tasmania belong to the first of these two periods — the Permo- 
Carboniferous. The chief localities where it is known to be developed, 
and the nature of the evidence, are as follow : — 
(a) First Glaciation in Permo-Carboniferous or Triassic Time. 
Tasmania. — (a.) Near Zeehan. Lat. 41° 50' S., long. 195° 20' E. 
Glacial conglomerate, containing well-rounded beautifully striated 
pebbles and boulders of rock foreign to the district ; is of no great thick- 
ness ; rests on Devonian sandstone ; height above sea-level, 3,000 feet. 
(i b .) Erratics at One Tree Point, Bruni Island, occurring in 
Marine Permo-Carboniferous strata at or about sea-level. Gan - 
gamopteris spathulata , McCoy, occurs on the same horizon. 
