^J^^'] Field Naturalists' Club — Proceedings. 109 



the cause or causes actuating its flow. Some maintain that 

 it is of Plutonic origin, while others aver it is strictly of meteoric 

 derivation. In his opinion, based on a careful study of acquired 

 facts, there can be no doubt that the water is wholly derived 

 from rainfall, and that it percolates through the porous beds 

 under influence of hydraulic conditions, which are primarily 

 responsible for its rise when tapped by bores. A series of bores 

 put down by the Agricultural Department between Pinnaroo 

 and Cow Plains proved that in the Victorian Mallee the artesian 

 basin was underlaid by a polyzoal rock series, mainly of Miocene 

 age. In all probability the salt lakes, so plentiful in the Mallee, 

 mark the site of depressions or troughs between the fold ridges, 

 where, by reason of earth fissures or fractures, the artesian 

 waters escape and percolate upwards to the surface. Enormous 

 deposits of gypsum or copi, up to 95 per cent, purity, occur in 

 many of these depressions, and afford one of the finest oppor- 

 tunities for the production of plaster of Paris in the world. 



The climate of the Mallee is extremely variable. One day it 

 might be so hot as to kill off the eucalypts, even though they 

 might be growing with their roots in the Murray, and the next 

 so cold as to necessitate the wearing of an overcoat in the 

 middle of the day. In favourable seasons the growth of grass 

 is so great as to hide from view the passage of a vehicle. 



In his opinion, the seeds of the Porcupine Grass were deserving 

 of the attention of experimentalists, for upon them stock 

 fattened quicker than on any other fodder in Australasia. 



The lecturette was illustrated by a number of lantern slides 

 depicting many interesting views of the varied physical aspects 

 and vegetation of the Mallee, its geological features, and the 

 process by which comparatively lightly timbered country is 

 rendered amenable to cultivation. 



In the discussion that followed, to which Messrs. Alexander, 

 Hardy, Keartland, Plumridge, Pescott, and Dr. C. S. Sutton 

 contributed, many questions were asked. Mr. Kenyon, in 

 reply, said that he had failed to ascertain when or by whom 

 the title " Mallee " was applied to the north-western part of 

 the State. It was so called as early as 1847. Various theories 

 had been advanced to account for the Pink Lakes of the Mallee. 

 Some contended, reasonably enough, that the colour was due 

 to algae, and others that it was due to manganese. So far as 

 he was aware, the nearest occurrence of typical Mallee vegeta- 

 tion to that in the neighbourhood of Bacchus Marsh was at 

 Bendigo and Ingle wood. Reference had been made to clumps 

 of Spinifex of large dimensions. The diameter of the largest 

 single plant he had seen was between 10 and 12 feet, its height 

 being about '5 feet, apart from the seed stalks. In so far as the 

 so-called water-bearing mallee eucalypt was concerned, he was 



