April, 1909.] THE VICTORIAN NATURALIST. 193 



southern side of the hill between numerous huge monoliths, and 

 then, scrambling between other huge blocks, made our way to the 

 western and higher end, where, amid the many sized and shaped 

 masses of rock, vantage points were secured, and the geology and 

 physiography of the locality demonstrated. It was shown how 

 the rock differs in chemical composition from the generality of 

 lavas, and this difference accounted for the shapes assumed by 

 the rock-masses owing to their peculiar manner of weathering. 

 Chemical analysis has shown that the rock contains a large 

 percentage of soda, and hence is termed " Solvsbergite," after a 

 town in Norway from whence a similar lava was first recorded. 

 Its occurrence is very rare, for nowhere else in Australia is it found 

 than there, at Camel's Hump, three miles away on the Macedon 

 Range, and at Brock's Monument, a hill on the other side of the 

 Dividing Range towards Romsey, both of which were visible from 

 our standpoint, but in neither case is the outcrop so interesting as 

 at Hanging Rock, Having given some consideration to the 

 physical features of the mount, we turned to the physiography, and 

 noted that, though situated north of the Dividing Range, it is 

 really south of some of the heads of the Deep Creek (Saltwater 

 River), which belongs to the southern drainage system, owing to the 

 fact that thereabouts the Divide is S-shaped, and curves round 

 to the north of the mount towards the Jim Jim, though its exact 

 position was hardly perceptible from our place of outlook ; thus 

 the drainage of the Rock finds its way to the Five-Mile Creek, 

 and thence to the Carnpaspe and the Murray. The hill rises 

 nearly 400 feet above the surrounding country, which is about 

 2,000 feet above sea level. The day was fairly clear, and, con- 

 sequently, we had a fine view of the country all round, extending 

 from the Trentham Ranges in the south-west to Wombat Hill 

 (Daylesford), Mt. Franklin, Mt. Tarrengower, Mt. Alexander, 

 Mt. William (Lancefield), and Macedon close at hand. Before 

 descending, a visit was paid to the eastern end of the hill, where 

 the rock-masses, some twenty to thirty feet high, are larger and 

 more majestic than at the other end. Many have been named 

 by visitors from fanciful resemblances to various objects. Several 

 appear ready to fall when the next earth tremor comes along, 

 and thus might disappear the group of stones usually selected 

 for illustrating the character of the mount. On our way down we 

 passed under the huge stone, supported at either end, which is 

 usually supi^osed to give the name " Hanging Rock " to the 

 locality. On the new tourist map of the Macedon district the 

 mount bears the name Mt. Diogenes, given to it by Major 

 Mitchell when he visited and named Mt. Macedon on his way 

 from Portland to the Murray in 1836. Its other name, " Dryden's 

 Monument," is derived from the name of an early settler in whose 

 run it was included. Some fairly large trees grew at one time on 



