Vol. XXVII. 

 1910 



"I Armitagb, Plant Remains in OHvine-Basalf. 21 



NOTES ON THE OCCURRENCE OF PLANT REMAINS 

 IN OLIVINE-BASALT, CLIFTON HILL QUARRY. 



By Richard W. Armitage. 



(Bead lefore the Field Naturalists' Chih of Victoria, I6th May, 1910.) 



Introduction. 



The communication I desire to make to the Club this evening 

 has for its object the placing on record of the discovery of plant 

 remains in an igneous rock, with a general description, which may 

 be amplified with greater detail at some later date. 



Occurrences such as this are so interesting and rare that I 

 have ventured to gather together references to, and records and 

 descriptions of, similar and allied occurrences in various parts of 

 the world, and to comment on them. 



The presence of plant remains in gravels, sand, and silt under 

 flows of volcanic rock, or in beds of clastic material between lava 

 flows of different ages, or imbedded in tuffs, is not altogether 

 uncommon, so that I shall confine the literary references almost 

 solely to records of plant life found actually in igneous rocks. 

 Such records are very few in number. 



Extracts from, and References to, Geological Literature. 



In reference to this subject in general, Dr. Scott (i) writes : — 

 " It will be readily imagined that lavas very rarely contain fossils. 

 Though the flows often overwhelm living beings, the intense heat 

 at once destroys them, seldom leaving a trace behind, though 

 charred tree-trunks are sometimes recognizably preserved. In 

 tuffs, on the other hand, fossils, especially those of plants, are 

 frequently well preserved, and tuffs formed under water have 

 fossils as abundantly as any other aqueous rocks." 



M. Fouque (2), describing an effusion of lava from Mt. Etna, 

 writes (trans.) : — "The lava of the eruption of 1865 has flowed 

 amongst a number of high trees ; the ground had opened to a 

 great length at the beginning of the eruption, forming a deep 

 irregular fissure, of which only the most widely opened parts are 

 new craters. Many of the trees had been either destroyed by 

 the great heat or else uprooted. However, many of them still 

 stood on each side of the fissure, although the ground had been 

 violently moved, and although an incandescent current of lava 

 had momentarily surrounded them. The trees thus preserved 

 were all without exception surrounded by a stony casing formed 

 of solidified lava. The inner surface of this casing had been 

 moulded on to the surface of the tree, sometimes representing all 

 the details of the bark with a surprising accuracy. The oute^ 

 rough irregular surface in every case presented, on the side on 

 which the current had impinged, a prismatic protuberance formed 

 by the lava, of which the tree had arrested the movement. A 

 few of these outer sheaths were intact, but the greater number 



