576
PROF. C. LAPWORTH ON THE GIRVAN SUCCESSION.
grounds of Millenderdale and Lag'gan, are still continuous with our
typical mass of Benan Hill. The remaining two, which occur upon
the ridges of Trowier and the Byne Hill, are now separated from the
Ben an ridge and each other by two gigantic strike -faults, which
have thrown down between them strata of much later geological
age. Not only is the present geographical arrangement of the rocks
of these areas almost demonstrative of their original continuity,
but their detailed study shows, as might have been expected, that
they agree precisely in all their petrological characters with their
prototypes of Benan Hill, and are similarly underlain by a group of
calcareous beds answering exactly to our limestone series of Auchen-
soul and the Stinchar.
3. Millenderdale area. — The most southerly of these supple-
mentary areas is formed by a narrow prolongation of the Benan Con-
glomerate, about three miles in length by half a mile in width, which
stretches from the typical area at Kinclaer viaduct upon the water of
Assel, into the heart of the Ballantrae rocks upon the water of Lendal.
It is distinctly interposed between these igneous rocks and the sheet
of Graptolitic flagstone which everywhere succeeds to the Benan
Conglomerate in the Girvan district. The peculiar relations of this
strip of conglomerate to the neighbouring Ballantrae rocks need not
detain us here. It will be sufficient for our present purpose to state
that a careful mapping of the area makes it clear that it forms,
generally speaking, a faulted anticlinal. Near its western extremity
the Stinchar Limestone emerges from below it in a group of old
quarries and natural exposures near the farmsteading of Millender-
dale. A few specimens of Saccammina Carteri, and Tetradium
Peachii are procurable from these limestones. In the deserted quarry
west of the steading, in spite of the shattered state of the beds, we
recognize with certainty the Nodular Flags (Ab 2 ) at its northern
extremity, followed by the Compact Limestones (Ab 3 ), for the extrac-
tion of which the excavation was made, and finally a few feet of the
superior greenish shales of the Lidymoyraptus-beds (Ab 4 ) are seen in
the stream-course to the south-west.
Fig. 10.
S.E.
-Basal Zones of the Girvan Succession, south-west
of Millenderdale.
N.W.
Ac. Benan Conglomerate.
Abe. Graptolitic shales with Diplograptus rugosus, Crypt, tricomis, &c.
Ax. Base of Grirvan Conglomerate.
Ax 2 . Well-bedded ashy conglomerates and sandstones.
Ax 1 . Coarse-breccias of fragments of igneous and altered rocks, with
interstratlfied purple sandstones and red and green grits and shales.
x. Igneous and altered rocks of Ballantrae Series,
f.