194. WALTER HOWCHIN 
floor below sea level. Then sedimentation followed, and there was 
laid down a great series of beds that reached forty or fifty thousand 
feet in thickness. 
The upper members of the series are characterized by purple 
sandstones and slates, quartzites, and numerous limestones, the 
whole being, typically, of a dark chocolate or purple color. Some 
of the limestones are highly fossiliferous, and contain, among others, 
representatives of the following genera: Olenellus, Ptychoparia, 
Dolichometo pus, Microdiscus, Leperditia, Stenotheca, Ophileta, Platy- 
ceras, Hyolithes, Salterella, Ambonychia, Obolella, Orthis, Orthisina, 
Hyalostelia, Girvanella. A limestone, near the upper limits of the 
series, consists almost entirely of Archaeocyathae, forming a “‘coral”’ 
reef 200 feet in thickness. 
The lower members, beginning with the Brighton limestone, 
near Adelaide, show the following succession in descending order: 
Brighton limestone, Tapley’s Hill ribbon-slates, Glacial till, Glen 
Osmond slates and quartzites, Upper phyllites, Black Hill (thick) 
quartzite, Lower phyllites, River Torrens limestone, Basal grits 
and conglomerates resting unconformably on a pre-Cambrian com- 
plex. The lower Cambrian beds are apparently destitute of organic 
remains, except for a few obscure traces of Radiolaria in the 
siliceous limestones. 
From the above order of succession the stratigraphical position 
of the glacial deposits is perfectly clear, and from their superior 
hardness, and association with an underlying quartzite, they form 
parallel ridges, being repeatedly brought to the surface by synclinal 
and anticlinal folds. The beds extend from near the south coast, 
for several hundreds of miles northward into the interior, having 
been traced as far north as Hergott (295° S. lat.); and in an east- 
and-west direction, from Port Augusta, at the head of Spencer 
Gulf, eastward to the Barrier ranges in New South Wales, a 
distance of 200 miles. 
Throughout this great extent of country the glacial beds pre- 
serve a remarkably uniform character. They attain a thickness 
of 1,500 feet, and for the most part consist of a bowlder clay or till, 
having a mudstone base which is gritty, and carries stones, irregu- 
larly disposed and of all sizes, up to 9 feet in diameter. The bowlder 
