188 Robert A. Kehle : 



fissure opened in or across the valley, a portion of the lava may 

 have found its way up the valley, in which case the point of issue- 

 would also mark a change in the gradient of the lava fields. There- 

 seems to be evidence of this to the north of Gembrook. 



The following is a tabulation of the strata passed through by 

 several bores put down by the Mines Department. The correla- 

 tion of the strata into their respective cycles is my own. 



'* High level leads," or the beds of streams belonging to the- 

 Pre-Older Basalt cycle, have been worked for gold at Gembrook, 

 Hoddle's Creek, Wandin, Upper Pakenham, Neerim, Mt. Leckie, 

 Lilydale and numerous otlier localities. The Quarterly Reports 

 of the Mining Registrars for the first and second decades after the 

 discovery of gold in Victoria, contain many references to these- 

 *' high level leads," and the difficulties encountered in working 

 them. The main difficulty was what is termed by miners " loss- 

 of level," due to an inadequate conception of the depth of the 

 valleys and their trend ; they often failed to tunnel into the lead at 

 a sufficient depth to get under it, a necessary procedure to ensure 

 efficient drainage. 



At AVilson's Quarry, in the Berwick residual, there is a thickness 

 of about seventy feet of lava. In the floor of the quarry leaf beds 

 are exposed, below which again is the bed of an old stream belong- 

 ing to the Pre-Older Basalt cycle. This old stream undoubtedly 

 rests on Palaeozoic slates and sandstones, which are exposed in the- 

 quarry. 



Alternating steep and gentle slopes of certain residuals suggest 

 the intercalation of softer strata, but if these softer beds were- 

 numerous or of appreciable thickness, sections of residuals would 

 correspond to the mesas of the Grand Canyon district of Colorado,- 

 to which they bear little resemblance. 



A survey of the evidence derived fromf borings and sections seems- 

 to permit of the following inferences : — 



(a) That from the outbi-eak to the cessation of the Older Vol- 

 canic activity there were periods of quiescence indicated 

 by interca^lated clays and sands. 



(b) That compared to the subsequent erosion, and accumulation/- 



of sediments in the lateral valleys, these periods of quies- 

 cence were of short duration. 



1 Vide Biblio;,^, No. 14. 



1 Vide Bibliog., No. 2. "The Uiiikaret.' 



