File:The Quarterly journal of the Geological Society of London (12683336893).jpg

1856..
SALTER LONGMYND FOSSILS.
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tened (a), folded (6), and very often obliterated. All these various
conditions are represented in one figure (woodcut, fig. 2), which
thus gives an average idea of the appearance of the markings when
perfect. The furrows themselves either slightly impress a plain sur-
face, as at a ; or run between convex ridges, as at c, when they are
closer and more branched.
Fig. 2. — Diagram of the restored form of peculiar Ripple-marks on
the Surfaces of the Flagstones near Church Stretton.
All these circumstances and the great irregularity of outline con-
vinced me, after careful search, that these were not fucoidal impres-
sions *, but mechanical markings produced by the minute drainage of
the surfaces when the water retired ; and hence that they afford
proofs of quiet littoral action.
Had the surface been merely sand, however fine, it is probable
that no such marks would have been produced, but that simple per-
colation would have taken place. But if a thin film of ochreous mud,
now a mere stain, were deposited on the surface, or washed into the
ripple-hollows, such a surface, being more retentive, might show the
tracks of the minute runnels of water as they flowed towards the
lowest part of the hollow before they were absorbed .
This seems but a slender datum on which to found a belief of the
proximity of land in these old Cambrian deposits. Their arenaceous
character, however, and the conglomerates which occur a little higher
up in the series, are better indications.
The conglomerates themselves, 120 feet thick to the W. of the
Portway, are well deserving study. They are chiefly round pebbles
of quartz-rock and vein-quartz ; but there is an occasional stray pebble
of syenite among them, as well as a great deal of felspathic matter de-
rived no doubt from the degradation of still older volcanic shores.

• Such as those described under the name of Dadalus by Marie Rouault, Bull.