Art. XIII. — Observations on the Geology of Mount Mary 

 and the Lower Werrlbee Valley. 



By a. E. KITSON, F.G.S. 

 [Read 12tli December, 1901,] 



On Quarter-sheet No. 8 S.W. of the Geological Survey of 

 "Victoria, published in 1864, a prominent hill, shaped like a 

 double horseshoe, attracts notice. This is Mount Mary, known 

 also as Green Hill. It has an explanatory note by the late Mr. 

 Daintree, who surveyed the area included in tlie sheet, which 

 reads : — " Blocks of white and yellow argillaceous sandstone con- 

 taining Miocene Tertiary fossils are imbedded in the scoriaceous 

 lava of Mount Mary, proving the extension of the Miocene strata 

 to this point under the lava of the plains, these being ejected 

 blocks during the eruption." 



This induced me to make a few visits to the place extending 

 over a period of several years. 



The geology of the district is interesting, and necessitates so 

 much careful observation that sufficient information has not yet 

 been collected to admit of any definite conclusions being formed 

 regarding certain of the rocks occurring along the Werribee 

 River. It is, therefore, with some diffidence that I submit these 

 few observations, perhaps somewhat prematurely, but brought 

 forward now as opportunities for further examination of the 

 locality may not present themselves within a reasonable time. 



On referring to the Quarter-sheet mentioned, it is seen that the 

 whole of the area included therein, except a fringe of alluvium 

 along the Werribee River, has been marked as of volcanic origin. 

 These volcanic rocks comprise basalts, scoriae and tuffs, and are 

 of considerable thickness, representing the products of several 

 eruptions from Mounts Mary and Cotterill, and unnamed points 

 of eruption on the east and west of Mount Mary. 



The summit of Mount Mary, apparently the highest point in 

 the locality, is somewhere about 500 feet above sea level. The 

 mount is of more than geological interest as it is the north- 



