chap. vii. Travertin, with Extinct Plants. 157 



Travertin with extinct plants. — Behind Hobart 

 Town there is a small quarry of a hard travertin, the 

 lower strata of which abound with distinct impressions 

 of leaves. Mr. Robert Brown had the kindness to 

 look at my specimens, and he informed me that there 

 are four or five kinds, none of which he recognises as 

 belonging to existing species. The most remarkable 

 leaf is palmate, like that of a fan-palm, and no plant 

 having leaves of this structure has hitherto been dis- 

 covered in Van Diemen's Land. The other leaves do 

 not resemble the most usual form of the Eucalyptus, 

 (of which tribe the existing forests are chiefly com- 

 posed,) nor do they resemble that class of exceptions to 

 the common form of the leaves of the Eucalyptus, which 

 occur in this island. The travertin containing this 

 remnant of a lost vegetation, is of a pale yellow colour, 

 hard, and in parts even crystalline ; but not compact, 

 and is everywhere penetrated by minute, tortuous, 

 cylindrical pores. It contains a very few pebbles of 

 quartz, and occasionally layers of chalcedonic nodules, 

 like those of chert in our Greensand. Erom the pure- 

 ness of this calcareous rock, it has been searched for in 

 other places, but has never been found. From this 

 circumstance, and from the character of the deposit, it 

 was probably formed by a calcareous spring entering a 

 small pool or narrow creek. The strata have subse- 

 quently been tilted and fissured ; and the surface has 

 been covered by a singular mass, with which, also, a 

 large fissure has been filled up, formed of balls of trap 

 embedded in a mixture of wacke and a white, earthv, 

 alumino-calcareous substance. Hence it would appear, 



vol. i. p. 504) as occurring in a basaltic amygdaloid, differs from this 

 substance, in remaining unchanged before the blowpipe, and in 

 blackening from exposure to the air. May we suppose that olivine, 

 in undergoing the remarkable change described at St. Jago, passes 

 through several states 1 



