234f 
Dr Hibbert on the Distribution 
Pursuing our circuit round the island east of the Point of 
Sragaster, we find a sandstone, which is coloured by green- 
earth, occupying an interval between masses of claystone-por- 
phyry. The direction of the strata is about N. 15° W,, dipping 
to the west at angles of about S0°. Again, to the east, as we 
approach the Kirksands, an amygdaloidal rock first appears, 
having a basis, consisting for the most part of ar^llaceous mat- 
ter combined with felspar, the cavities of which are filled with 
calcareous-spar, heavy-spar, fluor-spar, quartz crystals, chalce^ 
dony and gTeen-earth. This rock is alternated with thin beds 
of an indurated sandstone, occasionally passing into jasper. 
Here there are imperfect marks of stratification. At the Kirk- 
sands we have a sandstone manifesting a direction and dip nearly 
similar to those of the last strata, of the same name, described. 
Again, to the east, appears a conglomerated sandstone, alter- 
nated with an amygdaloidal rock, like the last noticed, the 
strata of which are vertical. East of the amygdaloidal rock we 
again meet with claystone-porphyry ; which mass is probably 
the continuation of a more northerly one, intercepting all the 
strata hitherto described. 
Crossing the porphyritic mass, which is imperfectly stratified, 
the second interval, supplied by strata, extends from the south- 
coast in a northerly direction to llousea Voe; it is limited to the 
east and north by the several porphyritic masses of Northhouse 
and Ollas Voe. These strata are chiefly of sandstone, which, 
south of Housea Voe, becomes conglomerate, containing small 
angular and rounded portions of the same rock, varied by the 
presence of green-earth : their direction is from N. 45° to 60° E., 
dipping to the west at angles of about S0“. North of Housea 
Voe, and extending to the head of Ollas Voe, are strata of 
sandstone alternated with amygdaloid. The stratification, 
when distinct, is in a direction of about N. S0° W., whilst the 
dip is to the west at angles of about 17°. 
Continuing our circuit round the island, in order to observe 
the relatbns of the porphyry, we find, to the north-east of Papa 
Stour, a conglomerate rock, variously consisting of portions of 
sandstone, claystone-porphyry, and green-earth. Strata of this 
rock are interposed in all positions from the vertical to the hori- 
zontal, between beds of claystone-porphyry. Here we may in 
some places disengage from the porphyry round, hollow concre- 
