57 



The Geology of the Neighbourhood of 

 Ga^wler. 



By G-ATiN ScouLAE, Corr. Memb. 

 [Read August 1, 1882.] 



[Plates II.] 



The geological features of the site of the town of Gawler are 

 somewhat diver sified aud interesting, for no less than four 

 different formations are represented, viz., the fundamental, or 

 " Pre-Silurian Rocks," as displayed on the north bank of the 

 South Para and south bank of the North Para Hivers respec- 

 tively ; Marine Miocenes well exposed in Thorup's Eavine to 

 the east ot* High- street ; Drift, or Pliocene deposits, through- 

 out the Church Hill and old Cemetery area, extending east aj^ 

 far as Blanche-street ; Quaternary, in the channels and adjacent 

 to the Para Elvers. 



Pee-Silueian Eocks. 



The surface configuration of the Pre-Silurian country, which 

 is situated to the east of Gawler Town, is undulating and 

 ridgy on the south-eastern section, whilst on the north-eastern 

 section it is that of isolated conical hills, which for the most 

 part are crowned with reconstructed Miocene detritus, but in 

 a few instances the capping is composed of the original 

 deposit. 



Clay Slate. — This rock comprises quite 98 per cent, of the 

 area occupied by the fundamental rocks, and may be studied 

 where outcropping from beneath the Miocenes on the north 

 bank of the South Para (Allotment 327, Hundred Nuriootpa) , 

 and on the north side of the town, on the south-east bank of 

 the North Para and bed of Whitlaw Gully, leading through 

 Section 7 of the same hundred. From these points the beds 

 can be traced in ascending order on either side of the Gawler 

 Marine Miocene escarpment, especially on the north bank of 

 the South Para may the various intercalations of the beds 

 be studied with advantage ; and in Section 3034, Hundred of 

 Barossa (Cockatoo Creek) a fine section of the slate is exposed 

 in a vertical position. There can be no doubt that in this 

 place we have revealed to us a synclinal axis, which is trace- 

 able in a northlv direction from the south bank of the South 



