54 
may have been a pyroxenic mineral. Of the rock constituents, part 
is blackish opacite, exhibiting here or there a felspar microlith, 
no doubt a fragment of scoria; part shows frequent felspar micro- 
liths, fragments probably of andesite; part is earthy, barely trans- 
lucent, and practically without effect on polarized light, very 
probably decomposed glass. With these viridite is interspersed. 
I think the materials are not water-worn. The rock, in short, is 
one of the ordinary fine-grained volcanic grits or rather coarse 
slates, with secondary micromineralogical changes. The red band 
consists of much finer materials, so that the discrimination and 
identification of the constituents is much more difficult; but I 
have no doubt it is a volcanic dust or mud. ‘The finest part of it 
changes rather abruptly into the ordinary coarser rock, though one 
or two fairly large fragments lie (boulder-fashion) in it, and here is 
a zone or streak of darker colour. On the other side it passes 
more gradually into the coarser rock. ‘The slide cut transverse to 
the plane of cleavage, shows that both the coarser and the finer 
fragments are compressed and elongated in the usual way. I 
cannot see any signs of a disturbance later than the date of the 
cleavage. TeGeb: 
