BY R. M. JOHNSTON, F.LS. 131 
cient precipitation to yield glaciers, any of which did not 
reach the sea, and probably were melted within their own 
valleys before reaching the 1,000 feet level. 
(3.) That the date at least of our most refrigerated period 
was probably isochronous, and mainly caused by the maxi- 
mum cycle of eccentricity of the earth’s orbit with winter in 
aphelion, probably near to the beginning of our neogene 
period, say, 850,000 years ago. 
(4.) That if the latter be true, it proves that the astrono- 
mical theory by itself (i.e, without concurrence of geo- 
eraphical conditions) would not adequately account for the ice 
age of Hurope and North America, nor for the absence of 
marked glacial phenomena among the earlier tertiary deposits 
of Hurope at points of time concurring with the earlier 
eycles of eccentricity of the earth’s orbit with winter in 
aphelion. 
I do not expect that my conclusions will be accepted at 
present by many geologists who have already attained to 
crystallised views on the matter, but even these may be pre- 
pared to allow that, granting the premises assumed by me, 
my conclusions follow as a logical necessity. 
PRINCIPAL SOURCES OF REFERENCE. 
YEAR. 
-(1) 1866—Formation of conglomerate beds near Darley, 
and on the .Wild Duck River, Bacchus Marsh, 
Victoria, ascribed by Selwyn to marine glacial 
transport. Selwyn Ulrich “ Notes on the 
Physical Geography and Mineralogy of Vic- 
toria,’ Melbourne, 1866. 
la 1875—Climate and time. Dr. Jas. Croll, 1875. 
(2) 1877—Glacial Phenomena in South Australia, Pro- 
fessor Ralph Tate, F.G.S., F.L.S. 
24 1880—The causes of glacial epochs. Alfred Russell 
, Wallace, “Island Life,” pp. 121-202, London, 
1880. 
