BY W. N. BENSON. 131 



vesicles. It may be mentioned here that well marked pillow- 

 structure has been observed in some amygdaloidal spilites occurr- 

 ing in the Woolomin Series in Portion 56, Parish of Loomberah, 

 by the bridge over the Peel River, eleven miles south of Tam- 

 worth. These rocks are highly altered, as much so as the majority 

 of the British spilites known to the writer. It cannot be doubted 

 that long strips of Bowling Alley (Middle Devonian) rocks are 

 faulted or folded in among the Woolomin Series, but the spilites 

 of these strips should be usually distinguishable from those belong- 

 ing to the Woolomin Series. Distinction between the two sets 

 of dolerites is not clear at present. 



Other rock-types occur that are cognate with the spilites, though 

 differing from them in varying degree. In Munro's Creek, com- 

 mencing at the Bazorback, and running thence up to the end of 



/\f'firoMn'ujrf Scale 

 Text-fig. 3. — Pavement of Pillow-Lava. 



the westernmost branch of it, is a series of pale grey green rocks. 



This mass was overlooked in the first survey, being thought to 



have been merely a rather altered tuff. Its eastern side adjacent 



to the serpentine is a flow-breccia, and traces of the same rock 



appear on the western side of the mass on the other side of the 



creek. The main mass is composed partly of a very fine-grained 



variolite with a most peculiar microscopical structure, partly of 



a subvariolitic porphyritic rock, and partly of a rock with an 



almost doleritic texture, intrusive into the finely granular or 



aphanitic variolitic rock. The porphyritic rock has a well 



developed pillow-structure, and several pavements of it are 



exposed in the bed of the creek. Fig. 3 illustrates one of these. 



