178 G. A. Cook: 



crystals arc not so magnetic, and are probably ilmenite. Then 

 again some of the crystals are not magnetic at all, but they show 

 pleochroism, high polarization colours, and all the characters of 

 tourmaline. The coarse sands were then examined, and a non- 

 magnetic Mark crystal picked out and examined chemically. This 

 examination showed the presence of iron and boron, thus confirming 

 the presence of tourmaline. This presence of magnetite, ilmenite 

 and tourmaline is not very important from the point of view of 

 origin of the sands, as they occur in such small quantities. How- 

 ever, it is interesting to note that N. R. Junner, 1 ft.Sc., finds then* 

 all in the Silurian sediments of Diamond Creek to the North-East 

 of Coburg. 



North of the Coburg cemetery in the V-shaped outcrop of tin* 

 series a small watercourse only 400 yards long has given rise to> 

 miniature buttes and canyons. The boundary of sands and Silu- 

 rian is V-shaped, with the apex of the V pointing Westwards, 

 This is due to the sands tilling up a depression in the Silurian, 

 possibly a pre-Tertiary stream valley. After the uplift of the area 

 following the deposition of the sands obliterating this stream, this 

 little local area was placed in a very unstable state as regards 

 erosion. It only required the digging of a gutter, some few years 

 back, for water to get a start down the site of the old pre-Tertiary 

 stream. The result has been a very rapid deepening of the bed of 

 the present watercourse, so that now it is in places 20 feet deep; 

 ami everywhere has vertical walls. A short distance down from the 

 highest portion of these " bad lands" the stream in places has up 

 to four parallel paths, each separated by a few yards. During 

 storms water flows rapidly at the bottom of these watercourses, often 

 20 feet l>elow the surface, and rapidly undercuts the soft sands. 

 The result is that often the different courses converge towards one 

 another, and further down the hill unite in various places, forming 

 a complicated network of watercourses under the hard surface of 

 matted soil on top. This top hard surface is often undercut to 

 Bueli an extent that it caves in, leading to the formation of little 

 islands or buttes. These buttes are generally only a few feet in 

 diameter, and stick up as pillars sometimes 2(1 feet high. They 

 are protected from rapid erosion by the top hard crust. 



Discussing this area in 1900 Dr. Lpach 2 emphasises the importance 

 of surface tension in the formation of these "bad lands.*' He 



Proc. Roy, Soc. Victoria, vol, xxv. (n.s.), Pt. ii., 191:?, p, ;s;J3. 

 Proi Roy. Soc, Victoria, vol. xix. (n.8.), Pt. ii., 19QE, pp 54-59. 



