26 



calcite with brucite are quite characteristic of limestones 

 found among areas of regional metamorphism where no 

 visible intrusive rock has influenced the phenomena, while 

 pyrites is common in all limestones, and is most widely dis- 

 tributed in all kinds of rocks, especially so in certain coal 

 seams. As for myself, I cannot pretend to speak with such 

 confidence as Mr. Stephens upon such a difficult question. I 

 can only state that I have carefully considered the evidences, 

 and have taken much time and trouble to gather and weigh 

 all facts bearing upon the subject, including the facts and 

 arguments of my friend. But notwithstsjiding this, I can 

 only still affirm that the opinions advanced by me have 

 merely the force of probability in my mind, from which all 

 doubt has not yet been wholly removed. 



The dynamical forces which upheaved and dislocated the 

 stratified rocks on the flanks of our mountain chains operated 

 probably at different intervals during a long course of time, 

 in which movements the mountain chains themselves would 

 also partake. There is abundant evidence throughout Tas- 

 mania of the eruption of intrusive greenstone rocks of more 

 recent date than the mesozoic stratified rocks, but that is no 

 reason for assuming that all the greenstone masses are of more 

 recent date than the marine mudstoneswhich so frequently abut 

 and overlie the older diabasic rocks of Tasmania. Nor have 

 we a right to assume that all movements of elevation are 

 immediately due to superficial intrusion of igneous rock. 

 Few mountain chains have been produced suddenly bv 

 cataclysms, and while I do not deny that cataclysms and 

 intrusive rocks have operated largely in producing important 

 modifications on the earth's surface, I am still inclined to 

 believe that the more important movements which have 

 resulted in raising stratified rocks to immense heights above 

 sea level, as on our mountain tiers, are often intermittent, 

 slow, and cover a vast period of time. 



It is hoped that the information now produced with 

 respect to important _ sections on the East Coast of North 

 Bruni may be of service in arriving at more satisfactory con- 

 clusions in all matters to which they relate. I am only 

 anxious for the truth of my opinions, and therefore shall 

 always be prepared to modify them in accordance with the 

 weight of available evidence. 



