65 



sequent to entombment in the marine or estuarine beds, be- 

 cause the stems are not infrequently found to be drilled by 

 Teredos." Such a commingling, as witnessed at Gawler, of 

 portions of comparatively stately land plants with marine 

 forms undoubtedly reminds us that a much greater annual rain- 

 fall took place in Australia during probably the close of the 

 Miocene period than what we at present witness. 



In concluding this sketch of the Miocene, I might instance 

 three notable sites where highly waterworn conglomerates 

 of Miocene age are found resting immediately upon the up- 

 turned edges of the old rocks, viz., in a small gully leading 

 into Whitlaw Gully on the south side, and south bank of the 

 JN'orth Para Eiver, both of which are situated in Section 12, 

 Hundred of Nuriootpa. Also on the eastern side of Section 

 479, at an elevation of not less than 400 feet, a ferruginous con- 

 glomerate of the same age and kind occurs. All these sections 

 are well exposed, and exhibit strong proof that they at some 

 distant period constituted portions of a Miocene shore-line. 



Drift, or Pliocexe. 



Area. — On account of the bold character of the pre-existing 

 surface immediately to the east of Murray-street, very little 

 of the formation has been preserved in situ east of the Miocene 

 escarpment. So far as the lower or western part of the town 

 is concerned, the deposits embracing the site of that part have 

 in a marked degree been laid down against a Miocene cliff, 

 which prior to the period of the Drift must have presented a 

 high and bold outline to the eastward, where Murray-street is 

 now situated. In defining the boundary of the main sheet of 

 this formation as developed at Gawler, I might here say a 

 small patch of it occurs on the north bank of the South Para 

 Eiver, in allotments 327 and 328, and continues to extend 

 north along High-street, embracing the site of the Old 

 Cemetery, Church Hill area, etc., Gawler jS^orth, and several 

 other small detached areas throughout the tract embraced in 

 the sketch. 



Thickness. — The vertical depth of this formation about 

 Gawler must vary with the increasing distance as w^e recede 

 from its outcrop. Tracing it from east to west, the thick- 

 ness of the formation at Gawler cannot be compared with what 

 it attains in parts of the eastern seaboard of St. Vincent's 

 Gulf; as, for an instance, the bore-hole at Port "Wakefield 

 shows the depth of the Drift to be there 292 feet below present 

 sea level, and the main mass of the formation on Gawler plains 

 attain an altitude of 450 feet above the present sea-line ; 

 therefore we have pretty conclusive evidence that a continuous 

 depression or sinking of Gulf St. Vincent and neighbourhood 



