380 PROCEEDINGS OF SECTION E. 



not enter upon a description of their character, except to state 

 that the general direction of the caves conforms to the existing 

 drainage system of the Limestone Creek, and is nearly parallel with 

 the strike of the beds of limestone and marble in which they occur. 

 One of the caves, which 1 have named Sheean's Cave, has quite a 

 number of lar^^e chambers and an abundance of stalactitic growths. 

 The roof of the entrance, and for some distance inward, consists 

 of a mass of white marble beautifully scalloped by the action of 

 running water. The general internal features of the cave is 

 similar to that of most caves elsewhere, ramifying chambers, with, 

 in some cases, narrow entrances, pillows of stalagmite, and 

 charming recesses glittering with calcite crystals and innumerable 

 pendant stalactites, forming an exquisite drapery over the ceilings. 



The source basin of the Mitta Mitta and the upper valley of 

 the Tambo River, are occupied by a great mass of Metamorphic 

 rocks, formed by the folding and crushing of the Silurian sedi- 

 ments, and the invasion of the crushed and altered sediments by 

 masses of intrusive granites and porphyries with their accompany- 

 ing dykes. In those localities where the sediments have been 

 most dislocated and compressed the metamorphism is must intense. 

 Broadly considered, we may define three well-marked zones or 

 stages of metamorphism. 'J he first represented by the argillites 

 are least altered. Members of the series usually indurated by 

 increasing silification, and in many cases the conversion of the 

 argillaceous material into a chloritic mineral. The second includes 

 the hornfels rocks, forming contact schists, in which micaceous 

 minerals are more abundant than in the argillites, and also pre- 

 sent more siliceous ingredients than the latter. The third group 

 embraces the regionally metamorphosed schists, the beds of mica- 

 schist and gneiss typically developed in the Livingstone Creek 

 Valley, near Omeo, and at Ensay. 



Many of the gneissic schists are so granitiform that it is only 

 by an examination of the beds in situ that their character as 

 metamorphosed sediments can be determined. In many places 

 the gradation from mica -schist to gneiss and metamorphic 

 granite can be traced. The genesis of the metamorphic rocks of 

 the Australian Alps is being so ably worked out by my friend Mr. 

 A. W. Howitt, F.G.S., that it would be a work of supererogation 

 for me to attempt a description of tlie lithological characters of 

 the metamorphic rocks and their associated igneous masses. 

 Having examined the areas described by Mr. Howitt and in many 

 localities with that gentleman, I can with pleasure testify to the 

 erudition and research shewn in his published writings on the 

 " Granites and Diorites of Swift's Creek." The metamorphic and 

 plutonic rocks of Omeo, and the sedimentary metamorphic and 

 igneous rocks of Ensay, where Mr. Howitt has formulated a 

 theory concerning the origin of the metamorphic schists, which 



