I 



BV II. I. JENSEN. 875 



problems remain untouched, and man}- of the interpretations given 

 in the present paper ma}' not be upheld by future investigators. 

 I hope to continue the research by degrees, as opportunities 

 arise, and other investigators may join. At all events it is hoped 

 that this paper may prove a beginning in the thorough investi- 

 gation of the geology of the Glass House Mountains. 



I desire to express my thanks to the officers of the Geological 

 Survey of Queensland for courtesy shown. I have particularly 

 to thank Mr. L. C. Ball, B.E., for the photographs from which 

 Plates xlvii.-l., accompanying this paper, were prepared, and for 

 many other favours. 



To Professor David and Mr. H. Stanley Jevons, of the Sydney 

 University, I am indebted for the encouragement they have given 

 in the present work, as well as for numerous useful hints, refer- 

 ences, etc. 



To Mr. Wm. Grigor, of Bankfoot House, Glass House 

 Mountains, I am indebted for directions as regards roads and 

 short cuts, and other useful information, as well as for many 

 other acts of good will. 



EXPLANATION OF PLATES. 

 Plate xlvi. 

 Map of the Glass House Mountains District. 



Plate xlvii. 

 Fig. L — Portion of Mt, Conowrin, showing columnar structure. 

 Fig. 2. — Mt. Beerwah. 



Plate xlviii. 



Fig. 3. — Mt. Conowrin, showing the inaccessible portion of the mountain, 



consisting entirely of vertical trachyte columns. 

 Fig. 4. — Mt. Tibrogargan, as seen from a railway train. 



Plate xlix. 

 Fig. 5. — Portion of railway cutting near Beerburrum Station, showing 

 trachyte dyke causing an anticline. 



Plate 1. 

 Fig. 6. — Bird's-eye view of the Glass House Mountains from Mt. Ngun Ngun. 

 Fig. 7. — Bird's-eye view of the Glass House Mountains from Mt. Mellum. 



(Fiers. 1-7 are from photoa by Mr. L. C. Ball, B.E., of the Geological Survey of 

 Queensland, and are reproduced by permission). 



