﻿Otft 



Vol. 64.] CA MB RIAlf AGE IN SOUTH AUSTRALIA. 249 



Fig. 7. —Sketch-section across the glacial beds of the Onkaparinga Valley. 

 (Length — about three-quarters of a mile.) 

 S. N. 



^'*^ _,— — T- 



-les^^a^^^ .''•y)*^^^ Glacial Till. ^^« *. 0. ^* ' ^o'J<^. ' "^^-^o' 



b C d e ^JJndevlyimj Quarlzites. 



[For the explanation of a, b, c, etc., see the accompanying descriptive section.] 



The following are the general features of the section : — 



Overlying Beds. 

 Miocene sands, sandstones, and gravels. 



Banded slates of Cambrian age (Tapley's-Hill Beds), with 2 feet 

 of impure limestone at their base. 



Gtlacial. Feet 



« = Third, or upper, till-bed.— Very characteristic. Agrittymud- 



stone, with numerous erratics measuring up to 3 feet in diameter, 



the latter being chiefly granites, gneisses, and quartzites. At one 



horizon there is a slaty belt, which is calcareous in part, showing a 



dipS. 20° E., at 40°. Estimated thickness 400 



6=Quartzite. — Massive, but somewhat irregular in occurrence, and 

 containing in one place a confused assemblage of pebbles. This hard 

 rock occupies the bed of the stream (along the strike), for 200 yards, 

 where it forms minor ridges and troughs, and weathers into large 



spheroidal masses. Thickness 14 



c=Second, or middle, till-bed. — Carries erratics, but is somewhat 



more slaty in structure than the first and third tills. Thickness ... 50 



«^=Quartzite. Has a dip of 25°. Thickness 8 



e= First, or lowest, till-bed. — Lithology similar to that of the 



third, or thick till. Thickness 120 



592 



Underlying Beds. 

 Laminated, fine-grained quartzite of wavy structure. The laminae 

 vary in thickness from a sixteenth of an inch to 1 inch. The 

 presence of strongly-marked cleavage in the till, and its complete 

 absence in the underlying wavy quartzites, makes a conspicuous 

 distinction between the two sets of beds. These beds present an 

 exact lithological agreement with the highest members of the 

 Miteham Quartzites which underlie the till in the Adelaide district. 



{b) The Sturt- Valley Sectioi). 

 (Figs. 8, 9, pp. 250, 252 & Pis. XX-XXIII.) 



The Sturt River is a small stream which rises near Mount Lofty 

 and finds its outlet in the estuary of the Patawalonga, a few miles 

 south of Adelaide. In Miocene times, a Cambrian peneplain, 



