This historic book may have numerous typos and missing text.
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(without typos) from the publisher. Not indexed. Not illustrated.
1873 Excerpt: ...relations of the Menevian (c), Ffestiniog (d),
Tremadoc (e), and Arenig Groups (f) in the district around
Portmadoc, N. Wales. By the Bev. A. Sedgwick, LL.D. 1847, and J. W.
Salter, 1853--7. The faults are aU by J. W. S. The strata, in
descending order, are: --f. Arenig (or Skiddaw) Group. Dark earthy
slates on a base of sandstone ( = Stiper Stones, Shropshire). e.
Tremadoc Group. Dark slates, iron stained, and with felspathic
beds--1500 feet thick. d. Ffestiniog Group. Thick flaky sandstones,
2000 feet, and a bed of block slate 300 feet. c. Menevian Group.
Dark slate and sandstone--only the top beds (with Olcnus
cataractcs). Middle Cambrian, e. Tremadoc Group. N. Wales. S.
Wales. (Sedgwick, 1847). e 1. Lower. Chiefly Black Slate. e 2.
Upper. Sandstones, grey and bluish: iron beds: ferruginous slate,
&c. e 1. Lower Tremadoc Slate (Salter, 1857). A natural
continuation of the Upper Lingula Flags. Chiefly black slate, but
very ochreous in part. The fauna is essentially Middle Cambrian,
but shews a tendency to include some few Lower Bala types, such as
Niobe, Psilocephalus, &c. The species however are all distinct,
even from those of the Arenig Group, and those of the Upper are
distinct from those of the Lower Tremadoc. We distinguish the
upper, e 2, from the lower group, e 1. Case and Column of Drawers.
Reference to Mccoy's Synopsis: and Figures of Genera. Names and
References; Observations, (be. Numbers and Localities. TRILOBITA.
Angelina Sedgwickii, Salter (Decade Geol. Surv. II. pi. 7). The
most abundant of the Tremadoc trilobites: allied to Olenus, but
with 15 body rings (Olenus has 14), and greatly larger than any
known species of that genus. Even size is a character of some
importance in classification. Occurs in all sorts of compressed
|Country of origin:
||246 x 189 x 2mm (L x W x T)
||Paperback - Trade
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