GLACIAL COMMITTEE. 199 
angles to the strike. It will probably be found that the 
beds repeat themselves in successive folds in the district 
referred to. These outcrops have an imdefinite extension 
northwards, and it is probable, as Dr. Chewing considers, 
that they extend in this direction as far as the Flinders 
Ranges on the west side of Lake Frome. This would give 
a line of outcrop (perhaps not continuous) of not less than 
200 miles. 
The glacial beds are assumed to be of Cambrian age, 
although this point can scarcely be regarded as definitely 
settled. The Till is interbedded in the series of the Mount 
Lofty Ranges, which the late Professor Ralph Tate regarded 
as of Archean age; and not only so, but the beds in question 
occupy a position in the series which the late Professor con- 
sidered the lowest horizon in sight. Rocks of Lower Cam- 
brian age, determined on paleontological evidence (presence 
of Archaeocyathine, &c.), occur a few miles to the south- 
east of the most southerly exposure of the Till, and it will 
probably not be difficult to trace the stratigraphical relation- 
ship which the Till bears to this Cambrian horizon. 
The remoteness in time of these geological phenomena, 
the enormous extent of the beds in their lineal outcrop, the 
relation of the geological facts to cognate questions, and the 
practical value which this very characteristic formation pos- 
sesses in establishing a datum-line in a very difficult geo 
logical country, invests this discovery with more than 
ordinary interest. 
One of the glacially-grooved pebbles from these Cam- 
brian (?) beds at Petersburg, in South Australia, is shown. 
This block was found firmly embedded zm situ in the matrix 
of the boulder-beds on the occasion of my revisiting these 
beds last September, in company with Mr. E. F. Pittman 
and Professor David. 
Note by T. W. Edgeworth David. 
The discovery just described by Mr. Walter Howchin is of 
immense scientific interest to geologists and paleontologists, and 
presents, too, a most fascinating problem to the meteorologist, 
astronomer, and physicist. It is only within the last few years 
that evidences of glaciation in early Paleozoic time, probably 
Cambrian, have been discovered in the Northern Hemisphere; 
and so far all these previous discoveries have been made close to 
the Arctic Circle. The most classical locality is that of the 
Varanger Fiord, on the boundary between Scandinavia and 
Russia, where Reusch has described boulder-beds (the Gaisha- 
beds) of probable Cambrian age, containing glacially-striated 
pebbles resting upon a glaciated surface, or pavement, of 
quartzite. The exact age of these glacial beds at the Varanger 
Fiord is somewhat doubtful, and they may range from as low as 
