182 VOLCANIC ROCKS OF SPRINGSURE. 



In the iminediate vicinity of Springsiire the volcanic 

 series of rocks have not been denuded through to the under- 

 lying Palaeozoic sediments. These sediments are believed 

 by the Geological Survey* to be of Lower BoAven age and 

 to be part f)f a belt about 10 miles wide which extends 

 from the south of Springsure in a northerly direction a 

 little to the west of Emerald and east of Clermont. To the 

 west of this belt the Star Series outcrops and the alunogen 

 deposit at Vandyke, 16 miles south-west from Springsure, 

 is in sandstones belonging to that series. To the east of 

 the belt the Upper Bo\\en Series outcrops. 



Springsure railway station is 1,057 feet above sea-level 

 and the height of the volcanic accumulations reaches 

 Approximately 2,000 feet in the case of Mt. Boorambool 

 which is about two miles west of the town. 



The immediate approach to Springsure by rail is along 

 i;he valley of the Sj^ringsure Creek which runs north between 

 the ridges of volcanic rocks. Boorambool Creek which 

 joins Springsure Creek a little to the north of Springsure 

 flows between Gill's Hill and Mt. Boorambool and around 

 the southern flank of the Mountain. These creeks have 

 denuded through the upper and middle series of volcanic 

 rocks but have not cut through the basal volcanic series of 

 basalts and basaltic agglomerateii. 



The investigations of the author were restricted almost 

 entirely to the volcanic masses to the Avest and north-west 

 of the town and .these are the Opal Ridge running north to 

 Gill's Hill, Mt. Boorambool or Ward's Hill and the Mountain. 

 Mt. Zamia is the name given by some peojole to the Mountain 

 and b}' others to Gill's Hill. In order to avoid confusion 

 the term Mt. Zamia will not be used throughout this paper. 

 Mr. McCahon, of Springsure, Avrites on this point : " After 

 very full enquiries from some of the oldest residents and 

 irom several bom and still living here I am inclined to think 

 that Mt. Zamia has been given on maps, plans, etc. to the 

 wrong mass. Many are positive that the correct name for 

 what you have called the " Mountain " is Mount Zamia 

 and the hill named Mt. Zamia on the maps is Gill's Hill." 



The Pinnacle Range to the north-east and Gap Range 

 to the east were not visited by the author but appear to be 



*Verbal communication from Mr. B. Dunstan, Chief Govt. Geologist. 



