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152 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. .Nov. 21,
At the Praia de Lagoa, near the preceding.
Natica praelonga, Deshayes. Pholadomya Royana?, UOrh.
At the Praia de Adrarga, north of the Cintra hills.
Nerinsea Archiraedis, D'Orb. Pecten striato-costatus, Goldf.
cylindrica, Voltz. Trigonia caudata, ^^rasse^r. .T.scabra,
Pyramidella sagittata, n. s. Morris's Catalogue.)
Ostraea colubrina, Lam.
At Fontanellas, north of Cintra.
Cardium corrugatum, n. s.
Both at the Praia de Adrarga and the Praia de Ma9ams the hme-
stones have been disturbed by various eruptions of trap, which appear
to have burst out during the formation of the subcretaceous beds, with
some of which they are very irregularly interstratified, while others
are displaced by them : in connection with the trap is a mass of ar-
gillaceous breccia, evidently of igneous origin and of considerable
thickness, which interrupts the series of stratified deposits. These
trappean beds are continued in a band round the Cintra hills, but
they do not belong to one formation, as described in my former paper
(Trans, vol. vi. p. 122), but pass through the different rocks which
encircle the granite.
The beds of the calcareous middle division of the subcretaceous
series cover the country north of Cintra for many miles, extending
beyond Mafra and Ericeira, and resting upon ferruginous sands, which
on the Caldas road are met with before reaching Torres Vedras.
The lowest part of the subcretaceous series is largely developed in
the district which lies to the north-east of Lisbon, bounded by the
Tagus from near Verdelha to Villa Franca. The great elevatoiy
movement which has thrown up the Jurassic rocks of Monte Junto
was continued with less intensity to the southward as far as Alhandra,
raising up all the lower beds of the subcretaceous series into an anti-
clinal of which the axis meets the Tagus at that place. This is seen
in section No. 4 (fig. 5), which shows the position of the beds along
the bank of the Tagus from Verdelha to Villa Franca.
Fig. 5.
Section No. 4. Bank of the Tagus near Alhandra.
Limestone alternating with sandstone. Sand, g
'3 2 a Subcretaceous Series.
Tertiary.
The same series of beds is crossed by the section No. 5 (fig. 6),
drawn nearly parallel to the last from Bucellas to Alenquer along a
line of traverse which I examined in some detail.