748 THE TIN DEPOSITS OF NEW ENGLAND, N.S.W., I., 



raagraatic water from the basalt on cooling. At all events, the 

 process worked on a disintegrated rock, and from aboAe down- 

 wards; for frequently only the upper portion has been cemented, 

 while a similar uncemented rock exists below. This is well 

 shown in Plate Ix.^ fig. 1. 



C alcareous Springs. — Amongst the earliest phases of volcanic 

 activity was the development of calcareous springs. Deposits of 

 lime-carbonate from these have been found in several localities. 

 These occur lying on the bed-rock (either granite or slate), and 

 not disintegrated w^ith the basalts. 



The next product of vulcanism seems to have been an ejection 

 of mud. There occurs in many places a very red clay, which 

 underlies the oldest basalt. That this is not a decomposition- 

 product of a basalt-flow in situ, is shown by the fact that, at 

 Newstead, a fragment of gum was found embedded in the clay. 



The Basalts. — Closely following this mud-deposit came the 

 first outpouring of the basalts. This manifestation was widespread 

 over the greater part of New England. 



From the fact that the lavas have covered the older river- 

 ■courses of the " Canon Cycle," it is evident that the basalts were 

 -extruded at the close of the period of uplift which gave rise to 

 •this cycle. The period of uplift which elapsed between the 

 formation of the " Stannifer Peneplain," of Andrews, and the 

 extrusion of the basalts was far greater than that between the 

 latter and the present day. This follows from the fact that, in 

 most places, erosion has not yet been sutficient to expose the deep 

 leads, even where the streams have been w^orking in basalt. 

 Tlie erogenic movements which caused the uplift of the 

 ''Stannifer Peneplain" were probably responsible for the 

 fractures through which the basalts were extruded. 



After the first outburst, a period of rest ensued, during which 

 ■erosion was active. That the period of rest following the earlier 

 basalts was a considerable one, may be gathered from the 

 following — At Elsmore a series of clays and lignites, filling a 

 broad valley and extending for some miles, have been formed by 



