554 Valley of Cop lap o. paet n. 



both eastward and westward. I will describe the 

 section seen on the eastern side of this mountain [D], 

 beginning at the base with the lowest bed visible in 

 the porphyritic conglomerate, and proceeding upwards 

 through the gypseous formation. Bed (1) consists of 

 reddish and brownish porphyry varying in character, 

 and in many parts highly amygdaloidal with carbonate 

 of lime, and with bright green and brown bole. Its 

 upper surface is throughout clearly denned, but the 

 lower surface is in most parts indistinct, and towards 

 the summit of the mountain [D] quite blended into 

 the intrusive porphyries. Bed (2), a pale lilac, hard 

 but not heavy stone, slightly laminated, including small 

 extraneous fragments, and imperfect as well as some 

 perfect and glassy crystals of feldspar; from 150 to 

 200 feet in thickness. When examining it in situ, 

 I thought it was certainly a true porphyry, but my 

 specimens now lead me to suspect that it possibly may 

 be a metamorphosed tuff. From its colour it could be 

 traced for a long distance, overlying in one part, quite 

 conformably to the porphyry of bed 1, and in another 

 not distant part, a very thick mass of conglomerate, 

 composed of pebbles of a porphyry chiefly like that of 

 bed 1 : this fact shows how the nature of the bottom 

 formerly varied in short horizontal distances. Bed (3), 

 white, much indurated tuff, containing minute pebbles, 

 broken crystals, and scales of mica, varies much in 

 thickness. This bed is remarkable from containing 

 many globular and pear-shaped, externally rusty balls, 

 from the size of an apple to a man's head, of very 

 tough, slate-coloured porphyry, with imperfect crystals 

 of feldspar : in shape these balls do not resemble pebbles, 

 and I believe that they are subaqueous volcanic bombs ; 

 they differ from subaerial bombs only in not being 

 vesicular. Bed (4), a dull purplish-red, hard conglo- 



