Vol. 58.] AMONG THE JURASSIC ROCKS OF SUTHERLAND. 299 
fragment of the original. Round the centra] core of breccia the 
ordinary strata form semicircles, all overlying it at the edge, and 
dipping away from it at the circumference (fig. 6, p. 298). This 
is well shown by the occurrence of a hard band in their midst, and 
having a band of shale between itself and the breccia. The stones 
in this breccia are hard false-bedded sandstones, not te be matched 
among the strata below. After passing this obstacle the strike and 
dip return to their normal direction, and the Hoplites and plant- 
remains reappear. 
Whatever explanation we may give of these phenomena, it must 
be such as takes account of the extremely local character of this 
mass of breccia, the slight general disturbance which it occasions, 
and the dissimilarity of the fragments to the ordinary Jurassic 
rocks of earlier date in the district. It seems to me to be best 
accounted for as a buried sea-stack broken up by the waves, or 
a collection in any other manner of fragments of more ancient 
rocks—by means, it might well be, of a raft of ice. The dis- 
turbance produced by its presence is not more than can be accounted 
for by the sinking of the soft shales, etc., on consolidation, and the 
resistance which the hard mass would oppose to subsequent general 
earth-movements. 
From this neighbourhood northward to Garty Point, I have not 
been able to make any observations along the shore. At that point 
Prof. Judd draws a fault, to the south of which he brings the 
Caithness Flags down to the coast-line ; and certainly immediately 
beyond the Point we find a repetition of the beds that we have seen 
before, north of Craigie Point. but here their strike is changed to 
about north-north-east and south-south-west, which has the effect 
of bringing them nearly parallel to the shore which runs in a 
north-easterly direction, and of spreading them out over long reaches, 
with very slow changes towards Helmsdale. 
‘The lowest beds seen opposite Midgarty Burn are the Cardioceras- 
alternans clays, which on the shore and in the cliff are full of that 
ammonite; and they are surmounted by astrong bed of grey nodular 
grit, which stands up in crags. A broad stretch of shore with masses 
of soft yellow sandstone, and black sands here and there, interferes 
with the visible succession of the rocks; but on the farther side the 
beds seem to continue the series without much change. 
Here we meet for the first time a new feature of great importance. 
Hitherto all the fossils met with north of the Loth River have been 
autochthonous, but here they are heterochthonous, and have been 
heaped up in masses of thick calcareous shells such as Rhynchonella 
Sutherlandie of great size, Perna quadrata, aud many others, 
including an ammonite like Perisphinctes mosquensis, but obscure. 
Such shells as these, with a speckled matrix, are mingled with Jarge 
angular pieces of rock, and aggregated together into a heap forming 
an outstanding boss on the shore. This is the beginning of the 
breccia-beds on the north side of Garty Point. The agent that 
collected these shells was obviously entering upon virgin soil and 
soon exhausted it, for in the upper part there are fewer calcareous 
