Quart. Journ. Geol. Soc. vol. xii. to face page 350. 



Since the above paper was in print my attention has been called to 

 a translation, in our Journal for February 1848, of the essay of 

 Prof. C. F. Naumann, " On the probable eruptive origin of several 

 kinds of gneiss, &c,," in which views very similar to those here en- 

 tertained are given, in relation to the laminated and fissile structure 

 of the crystalline plutonic rocks, — reference being there made to my 

 observations on the Trachytes of Ponza and Palmarola, and the 

 Phonolites generally, as illustrating the mode of formation of gneiss 

 and mica-schist, and leading to the inference that these rocks owe 

 their structural parallelism rather to pressure and friction accom- 

 panying their eruptive protrusion, than to the effect of metamorphic 

 action upon sedimentary strata. I rejoice to find my early views on 

 the subject supported by such high authority, and trust that other 

 geologists of weight and influence may thereby be induced to give 

 them their unbiassed consideration. 



