Geology of Warrandyte Ooldjield. 529 



Some of the vertical joints are so close together that they 

 have the appearance of incipient cleavage. At a quarry on the 

 MuUuni Mulluui Creek, there is a band of rock about 2 feet 6 

 inches broad and about 15 feet high, divided into regular ver- 

 tical lines from 1 to 3 inches apart. No other division planes 

 are visible. On each side of this band ordinary well marked 

 bedding planes are developed with vertical joints a little dis- 

 tance apart. On close examination similar rocks are seen to 

 continue across the particular band. The jointing has been so 

 minute and regular as to obliterate the bedding planes in this 

 portion of the rocks. Curved joints are found above the en- 

 trance tunnel at Pound Bend. In no other locality in the area 

 have I noticed similar joints. 



The most interesting jointing is in connection with the con- 

 glomerates and grits at Warrandyte. Some of these rocks are 

 fairly tough. When jointed, even in blocks 3 or 4 inches in 

 size, the hard cpuirtz, quartzite, chert, and sandstone pebbles 

 are often seen to Ije cut through as smoothly and evenly, as 

 if they were plastic materials ctit with a knife. That this is 

 simply due to jointing is shown by the absence of slickensides, 

 and by the very small and close planes that occur. It proves 

 that the force exerted was enormous. De la Beche (13, p. 

 628) notices the same feature in the conglomerates of the Old 

 Red Sandstone in the County of Waterford, Ireland, where 

 '■ huge masses of the conglomerate, composed of quartz pebbles 

 and of portions of older arenaceous and other deposits, as also 

 of igneous rocks, in certain localities, may be smoothly cut 

 through and separated by joint planes." He also states that the 

 division presents no trace of dislocation or movement, the faces 

 of the divided parts of the pebbles fitting each other exactly. 

 When the Warrandyte conglomerates are broken with the 

 hammer, the fracture is irregular, leaving the pebbles intact. 



(d) Fvisils and Cuiiditio/is of Sediineiitation. 



At Warrandyte in the coarser grits and conglomerates, fossils 

 are often abundant. They consist mainly of corals and poly/.ou, 

 btit the species are apparently not numerous. The old Victoriaii 

 Geological Stirvey foiuid some fossils in the finer grained rocks, 



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