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CHRONOLOGICAL CLASSIFICATION OF ROCKS.
Aqueous, Plutonic, volcanic, and metamorphic
Rocks considered chronologically. — Terms Primary,
Secondary, and Tertiary; Palæozoic, Mesozoic, and Cainozoic
explained. — On the different Ages of the aqueous Rocks.
— Three principal Tests of relative Age: Superposition,
Mineral Character, and Fossils. — Change of Mineral
Character and Fossils in the same continuous Formation. —
Proofs that distinct Species of Animals and Plants have lived at
successive Periods. — Distinct Provinces of indigenous
Species. — Great Extent of single Provinces. —
Similar Laws prevailed at successive Geological Periods. —
Relative Importance of mineral and palæontological
Characters. — Test of Age by included Fragments. —
Frequent Absence of Strata of intervening Periods. —
Tabular Views of fossiliferous Strata.
Chronology of Rocks.— In the first chapter it was
stated that the four great classes of rocks, the aqueous, the
volcanic, the Plutonic, and the metamorphic, would each be
considered not only in reference to their mineral characters, and
mode of origin, but also to their relative age. In regard to the
aqueous rocks, we have already seen that they are stratified,
that some are calcareous, others argillaceous or siliceous, some
made up of sand, others of pebbles; that some contain
fresh-water, others marine fossils, and so forth; but the student
has still to learn which rocks, exhibiting some or all of these
characters, have originated at one period of the earth’s
history, and which at another.
To determine this point in reference to the fossiliferous
formations is more easy than in any other class, and it is
therefore the most convenient and natural method to begin by
establishing a chronology for these strata, and then to refer as
far as possible to the same divisions, the several groups of
Plutonic, volcanic, and metamorphic rocks. Such a system of
classification is not only recommended by its greater clearness
and facility of application, but is also best fitted to strike
the imagination by bringing into one view the contemporaneous
revolutions of the inorganic and organic creations of former
times. For the sedimentary formations are most readily
distinguished by the different species of fossil animals and
plants which they inclose, and of which one assemblage after
another has flourished and then disappeared from the earth in
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In the present work, therefore, the four great classes of
rocks, the aqueous, Plutonic, volcanic, and metamorphic, will
form four parallel, or nearly parallel, columns in one
chronological table. They will be considered as four sets of
monuments relating to four contemporaneous, or nearly
contemporaneous, series of events. I shall endeavour, in a
subsequent chapter on the Plutonic rocks, to explain the manner
in which certain masses belonging to each of the four classes of
rocks may have originated simultaneously at every geological
period, and how the earth’s crust may have been continually
remodelled, above and below, by aqueous and igneous causes, from
times indefinitely remote. In the same manner as aqueous and
fossiliferous strata are now formed in certain seas or lakes,
while in other places volcanic rocks break out at the surface,
and are connected with reservoirs of melted matter at vast depths
in the bowels of the earth, so, at every era of the past,
fossiliferous deposits and superficial igneous rocks were in
progress contemporaneously with others of subterranean and
Plutonic origin, and some sedimentary strata were exposed to
heat, and made to assume a crystalline or metamorphic
It can by no means be taken for granted, that during all these
changes the solid crust of the earth has been increasing in
thickness. It has been shown, that so far as aqueous action is
concerned, the gain by fresh deposits, and the loss by
denudation, must at each period have been equal (see above, Chap.
VI, p. 96); and in like manner, in the inferior portion of the
earth’s crust, the acquisition of new crystalline rocks, at
each successive era, may merely have counterbalanced the loss
sustained by the melting of materials previously consolidated. As
to the relative antiquity of the crystalline foundations of the
earth’s crust, when compared to the fossiliferous and
volcanic rocks which they support, I have already stated, in the
first chapter, that to pronounce an opinion on this matter is as
difficult as at once to decide which of the two, whether the
foundations or superstructure of an ancient city built on wooden
piles may be the oldest. We have seen that, to answer this
question, we must first be prepared to say whether the work of
decay and restoration had gone on most rapidly above or below;
whether the average duration of the piles has exceeded that of
the buildings, or the contrary. So also in regard to the relative
age of the superior and inferior portions of the earth’s
crust; we can not hazard even a conjecture on this point, until
we know whether, upon an average, the power of water above, or
that of heat below, is most efficacious in giving new forms to
[ 123 ]
The early geologists gave to all the crystalline and
non-fossiliferous rocks the name of Primitive or Primary, under
the idea that they were formed anterior to the appearance of life
upon the earth, while the aqueous or fossiliferous strata were
termed Secondary, and alluviums or other superficial deposits,
Tertiary. The meaning of these terms, has, however, been
gradually modified with advancing knowledge, and they are now
used to designate three great chronological divisions under which
all geological formations can be classed, each of them being
characterised by the presence of distinctive groups of organic
remains rather than by any mechanical peculiarities of the strata
themselves. If, therefore, we retain the term
“primary,” it must not be held to designate a set of
crystalline rocks some of which have been proved to be even of
Tertiary age, but must be applied to all rocks older than the
secondary formations. Some geologists, to avoid misapprehension,
have introduced the term Palæozoic for primary, from
palaion, “ancient,” and zoon, “an
organic being,” still retaining the terms secondary and
tertiary; Mr. Phillips, for the sake of uniformity, has proposed
Mesozoic, for secondary, from mesos, “middle,”
etc.; and Cainozoic, for tertiary, from kainos,
“recent,” etc.; but the terms primary, secondary, and
tertiary have the claim of priority in their favour, and are of
It may perhaps be suggested that some metamorphic strata, and
some granites, may be anterior in date to the oldest of the
primary fossiliferous rocks. This opinion is doubtless true, and
will be discussed in future chapters; but I may here observe,
that when we arrange the four classes of rocks in four parallel
columns in one table of chronology, it is by no means assumed
that these columns are all of equal length; one may begin at an
earlier period than the rest, and another may come down to a
later point of time, and we may not be yet acquainted with the
most ancient of the primary fossiliferous beds, or with the
newest of the hypogene.
For reasons already stated, I proceed first to treat of the
aqueous or fossiliferous formations considered in chronological
order or in relation to the different periods at which they have
There are three principal tests by which we determine the age
of a given set of strata; first, superposition; secondly, mineral
character; and, thirdly, organic remains. Some aid can
occasionally be derived from a fourth kind of proof, namely, the
fact of one deposit including in it fragments of a pre-existing
rock, by which the relative ages of the two may, even in the
absence of all other evidence, be determined.
[ 124 ]
Superposition.—The first and principal test of
the age of one aqueous deposit, as compared to another, is
relative position. It has been already stated, that, where strata
are horizontal, the bed which lies uppermost is the newest of the
whole, and that which lies at the bottom the most ancient. So, of
a series of sedimentary formations, they are like volumes of
history, in which each writer has recorded the annals of his own
times, and then laid down the book, with the last written page
uppermost, upon the volume in which the events of the era
immediately preceding were commemorated. In this manner a lofty
pile of chronicles is at length accumulated; and they are so
arranged as to indicate, by their position alone, the order in
which the events recorded in them have occurred.
In regard to the crust of the earth, however, there are some
regions where, as the student has already been informed, the beds
have been disturbed, and sometimes extensively thrown over and
turned upside down. (See p. 73, p. 87.) But an experienced geologist
can rarely be deceived by these exceptional cases. When he finds
that the strata are fractured, curved, inclined, or vertical, he
knows that the original order of superposition must be doubtful,
and he then endeavours to find sections in some neighbouring
district where the strata are horizontal, or only slightly
inclined. Here, the true order of sequence of the entire series
of deposits being ascertained, a key is furnished for settling
the chronology of those strata where the displacement is
Mineral Character.—The same rocks may often be
observed to retain for miles, or even hundreds of miles, the same
mineral peculiarities, if we follow the planes of stratification,
or trace the beds, if they be undisturbed, in a horizontal
direction. But if we pursue them vertically, or in any direction
transverse to the planes of stratification, this uniformity
ceases almost immediately. In that case we can scarcely ever
penetrate a stratified mass for a few hundred yards without
beholding a succession of extremely dissimilar rocks, some of
fine, others of coarse grain, some of mechanical, others of
chemical origin; some calcareous, others argillaceous, and others
siliceous. These phenomena lead to the conclusion that rivers and
currents have dispersed the same sediment over wide areas at one
period, but at successive periods have been charged, in the same
region, with very different kinds of matter. The first observers
were so astonished at the vast spaces over which they were able
to follow the same homogeneous rocks in a horizontal direction,
that they came hastily to the opinion, that the whole
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globe had been environed by a succession of distinct aqueous
formations, disposed round the nucleus of the planet, like the
concentric coats of an onion. But, although, in fact, some
formations may be continuous over districts as large as half of
Europe, or even more, yet most of them either terminate wholly
within narrower limits, or soon change their lithological
character. Sometimes they thin out gradually, as if the supply of
sediment had failed in that direction, or they come abruptly to
an end, as if we had arrived at the borders of the ancient sea or
lake which served as their receptacle. It no less frequently
happens that they vary in mineral aspect and composition, as we
pursue them horizontally. For example, we trace a limestone for a
hundred miles, until it becomes more arenaceous, and finally
passes into sand, or sandstone. We may then follow this
sandstone, already proved by its continuity to be of the same
age, throughout another district a hundred miles or more in
Organic Remains.—This character must be used as a
criterion of the age of a formation, or of the contemporaneous
origin of two deposits in distant places, under very much the
same restrictions as the test of mineral composition.
First, the same fossils may be traced over wide regions, if we
examine strata in the direction of their planes, although by no
means for indefinite distances. Secondly, while the same fossils
prevail in a particular set of strata for hundreds of miles in a
horizontal direction, we seldom meet with the same remains for
many fathoms, and very rarely for several hundred yards, in a
vertical line, or a line transverse to the strata. This fact has
now been verified in almost all parts of the globe, and has led
to a conviction that at successive periods of the past, the same
area of land and water has been inhabited by species of animals
and plants even more distinct than those which now people the
antipodes, or which now co-exist in the arctic, temperate, and
tropical zones. It appears that from the remotest periods there
has been ever a coming in of new organic forms, and an extinction
of those which pre-existed on the earth; some species having
endured for a longer, others for a shorter, time; while none have
ever reappeared after once dying out. The law which has governed
the succession of species, whether we adopt or reject the theory
of transmutation, seems to be expressed in the verse of the
Natura il fece, e poi ruppe la stampa.
Nature made him, and then broke the
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And this circumstance it is, which confers on fossils their
highest value as chronological tests, giving to each of them, in
the eyes of the geologist, that authority which belongs to
contemporary medals in history.
The same can not be said of each peculiar variety of rock; for
some of these, as red marl and red sandstone, for example, may
occur at once at the top, bottom, and middle of the entire
sedimentary series; exhibiting in each position so perfect an
identity of mineral aspect as to be undistinguishable. Such exact
repetitions, however, of the same mixtures of sediment have not
often been produced, at distant periods, in precisely the same
parts of the globe; and even where this has happened, we are
seldom in any danger of confounding together the monuments of
remote eras, when we have studied their imbedded fossils and
their relative position.
Zoological Provinces.—It was remarked that the
same species of organic remains can not be traced horizontally,
or in the direction of the planes of stratifications for
indefinite distances. This might have been expected from analogy;
for when we inquire into the present distribution of living
beings, we find that the habitable surface of the sea and land
may be divided into a considerable number of distinct provinces,
each peopled by a peculiar assemblage of animals and plants. In
the “Principles of Geology,” I have endeavoured to
point out the extent and probable origin of these separate
divisions; and it was shown that climate is only one of many
causes on which they depend, and that difference of longitude as
well as latitude is generally accompanied by a dissimilarity of
As different seas, therefore, and lakes are inhabited, at the
same period, by different aquatic animals and plants, and as the
lands adjoining these may be peopled by distinct terrestrial
species, it follows that distinct fossils will be imbedded in
contemporaneous deposits. If it were otherwise—if the same
species abounded in every climate, or in every part of the globe
where, so far as we can discover, a corresponding temperature and
other conditions favourable to their existence are
found—the identification of mineral masses of the same age,
by means of their included organic contents, would be a matter of
still greater certainty.
Nevertheless, the extent of some single zoological provinces,
especially those of marine animals, is very great; and our
geological researches have proved that the same laws prevailed at
remote periods; for the fossils are often identical throughout
wide spaces, and in detached deposits, consisting of rocks
varying entirely in their mineral nature.
[ 127 ]
The doctrine here laid down will be more readily understood,
if we reflect on what is now going on in the Mediterranean. That
entire sea may be considered as one zoological province; for
although certain species of testacea and zoophytes may be very
local, and each region has probably some species peculiar to it,
still a considerable number are common to the whole
Mediterranean. If, therefore, at some future period, the bed of
this inland sea should be converted into land, the geologist
might be enabled, by reference to organic remains, to prove the
contemporaneous origin of various mineral masses scattered over a
space equal in area to half of Europe.
Deposits, for example, are well known to be now in progress in
this sea in the deltas of the Po, Rhone, Nile, and other rivers,
which differ as greatly from each other in the nature of their
sediment as does the composition of the mountains which their
drain. There are also other quarters of the Mediterranean, as off
the coast of Campania, or near the base of Etna, in Sicily, or in
the Grecian Archipelago, where another class of rocks is now
forming; where showers of volcanic ashes occasionally fall into
the sea, and streams of lava overflow its bottom; and where, in
the intervals between volcanic eruptions, beds of sand and clay
are frequently derived from the waste of cliffs, or the turbid
waters of rivers. Limestones, moreover, such as the Italian
travertins, are here and there precipitated from the waters of
mineral springs, some of which rise up from the bottom of the
sea. In all these detached formations, so diversified in their
lithological characters, the remains of the same shells, corals,
crustacea, and fish are becoming inclosed; or, at least, a
sufficient number must be common to the different localities to
enable the zoologist to refer them all to one contemporaneous
assemblage of species.
There are, however, certain combinations of geographical
circumstances which cause distinct provinces of animals and
plants to be separated from each other by very narrow limits; and
hence it must happen that strata will be sometimes formed in
contiguous regions, differing widely both in mineral contents and
organic remains. Thus, for example, the testacea, zoophytes, and
fish of the Red Sea are, as a group, extremely distinct from
those inhabiting the adjoining parts of the Mediterranean,
although the two seas are separated only by the narrow isthmus of
Suez. Calcareous formations have accumulated on a great scale in
the Red Sea in modern times, and fossil shells of existing
species are well preserved therein; and we know that at the mouth
of the Nile large
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deposits of mud are amassed, including the remains of
Mediterranean species. It follows, therefore, that if at some
future period the bed of the Red Sea should be laid dry, the
geologist might experience great difficulties in endeavouring to
ascertain the relative age of these formations, which, although
dissimilar both in organic and mineral characters, were of
But, on the other hand, we must not forget that the
north-western shores of the Arabian Gulf, the plains of Egypt,
and the Isthmus of Suez, are all parts of one province of
terrestrial species. Small streams, therefore, occasional
land- floods, and those winds which drift clouds of sand along
the deserts, might carry down into the Red Sea the same shells of
fluviatile and land testacea which the Nile is sweeping into its
delta, together with some remains of terrestrial plants and the
bones of quadrupeds, whereby the groups of strata before alluded
to might, notwithstanding the discrepancy of their mineral
composition and marine organic fossils, be shown to have
belonged to the same epoch.
Yet, while rivers may thus carry down the same fluviatile and
terrestrial spoils into two or more seas inhabited by different
marine species, it will much more frequently happen that the
coexistence of terrestrial species of distinct zoological and
botanical provinces will be proved by the identity of the marine
beings which inhabited the intervening space. Thus, for example,
the land quadrupeds and shells of the valley of the Mississippi,
of central America, and of the West India islands differ very
considerably, yet their remains are all washed down by rivers
flowing from these three zoological provinces into the Gulf of
In some parts of the globe, at the present period, the line of
demarkation between distinct provinces of animals and plants is
not very strongly marked, especially where the change is
determined by temperature, as it is in seas extending from the
temperate to the tropical zone, or from the temperate to the
arctic regions. Here a gradual passage takes place from one set
of species to another. In like manner the geologist, in studying
particular formations of remote periods, has sometimes been able
to trace the gradation from one ancient province to another, by
observing carefully the fossils of all the intermediate places.
His success in thus acquiring a knowledge of the zoological or
botanical geography of very distant eras has been mainly owing to
this circumstance, that the mineral character has no tendency to
be affected by climate. A large river may convey yellow or red
mud into some part of the ocean, where
[ 129 ]
it may be dispersed by a current over an area several hundred
leagues in length, so as to pass from the tropics into the
temperate zone. If the bottom of the sea be afterwards upraised,
the organic remains imbedded in such yellow or red strata may
indicate the different animals or plants which once inhabited at
the same time the temperate and equatorial regions.
It may be true, as a general rule, that groups of the same
species of animals and plants may extend over wider areas than
deposits of homogeneous composition; and if so,
palæontological characters will be of more importance in
geological classification than the test of mineral composition;
but it is idle to discuss the relative value of these tests, as
the aid of both is indispensable, and it fortunately happens,
that where the one criterion fails, we can often avail ourselves
of the other.
Test by included Fragments of older Rocks.—It was
stated, that proof may sometimes be obtained of the relative date
of two formations by fragments of an older rock being included in
a newer one. This evidence may sometimes be of great use, where a
geologist is at a loss to determine the relative age of two
formations from want of clear sections exhibiting their true
order of position, or because the strata of each group are
vertical. In such cases we sometimes discover that the more
modern rock has been in part derived from the degradation of the
older. Thus, for example, we may find chalk in one part of a
country, and in another strata of clay, sand, and pebbles. If
some of these pebbles consist of that peculiar flint, of which
layers more or less continuous are characteristic of the chalk,
and which include fossil shells, sponges, and foraminifera of
cretaceous species, we may confidently infer that the chalk was
the oldest of the two formations.
Chronological Groups.—The number of groups into
which the fossiliferous strata may be separated are more or less
numerous, according to the views of classification which
different geologists entertain; but when we have adopted a
certain system of arrangement, we immediately find that a few
only of the entire series of groups occur one upon the other in
any single section or district.
The thinning out of individual strata was before described (p. 42). But let the diagram (Fig.
84) represent seven fossiliferous groups, instead of as many
strata. It will then be seen that in the middle all the
superimposed formations are present; but in consequence of some
of them thinning out, No. 2 and No. 5 are absent at one extremity
of the section, and No. 4 at the other.
[ 130 ]
In another diagram (Fig. 85), a real section of the geological
formations in the neighbourhood of Bristol and the Mendip Hills
is presented to the reader, as laid down on a true scale by
Professor Ramsay, where the newer groups 1, 2, 3, 4 rest
unconformably on the formations 5, 6, 7 and 8. At the southern
end of the line of section we meet with the beds No. 3 (the New
Red Sandstone) resting immediately on Nos. 7 and 8, while farther
north as at Dundry Hill in Somersetshire, we behold eight groups
superimposed one upon the other, comprising all the strata from
the inferior Oolite, No. 1, to the coal and carboniferous
limestone. The limited horizontal extension of the groups 1 and 2
is owing to denudation, as these formations end abruptly, and
have left outlying patches to attest the fact of their having
originally covered a much wider area.
In order, therefore, to establish a chronological succession
of fossiliferous groups, a geologist must begin with a single
section in which several sets of strata lie one upon the other.
He must then trace these formations, by attention to their
mineral character and fossils, continuously, as far as possible,
from the starting-point. As often as he meets with new groups, he
must ascertain by superposition their age relatively to those
first examined, and thus learn how to intercalate them in a
tabular arrangement of the whole.
By this means the German, French, and English geologists
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have determined the succession of strata throughout a great
part of Europe, and have adopted pretty generally the following
groups, almost all of which have their representatives in the
[ 132 ]
TABULAR VIEW OF THE FOSSILIFEROUS STRATA,
SHOWING THE ORDER OF SUPERPOSITION OR CHRONOLOGICAL
SUCCESSION OF THE PRINCIPAL GROUPS DESCRIBED IN THIS
Shells and mammals, all of living species.
Clyde marine strata, with canoes (p.
Danish kitchen middens (p.
Lacustrine mud, with remains of Swiss lake-dwellings (p. 148).
Marine strata inclosing Temple of Serapis, at Puzzuoli (p. 146).
Shells, recent mammalia in part extinct.
Loam of Brixham cave, with flint implements and bones of extinct
and living quadrupeds (p.
Drift near Salisbury, with bones of mammoth, Spermophilus, and
stone implements (p. 161).
Glacial drift of Scotland, with marine shells and remains of
mammoth (p. 176.
Erratics of Pagham and Selsey Bill (p. 182).
Glacial drift of Wales, with marine fossil shells, about 1400
feet high, on Moel Tryfaen (p.
Dordogne caves of the reindeer period (p. 150).
Older valley-gravels of Amiens, with flint implements and bones
of extinct mammalia (p.
Loess of Rhine (p. 154).
Ancient Nile-mud forming river-terraces (p. 154).
Loam and breccia of Liege caverns, with human remains (pp. 156, 157).
Australian cave breccias, with bones of extinct marsupials (p. 158).
Glacial drift of Northern Europe (p.
166, p. 174).
TERTIARY OR CAINOZOIC
The shells almost all of living species.
Bridlington beds, marine Arctic fauna (p. 189).
Glacial boulder formation of Norfolk cliffs (p. 190).
Forest-bed of Norfolk cliffs, with bones of Elephas
meridionalis, etc. (p.
Chillesford and Aldeby beds, with marine shells, chiefly Arctic
Norwich crag (p. 193).
Eastern base of Mount Etna, with marine shells (p. 204).
Sicilian calcareous and tufaceous strata (p. 205, 206).
Lacustrine strata of Upper Val d’Arno (p. 207).
Madeira leaf-bed and land-shells (p.
Extinct species of
shells forming a
Red crag of Suffolk, marine shells, some of northern forms (p. 194, 195).
White or coralline crag of Suffolk (p. 197).
Antwerp crag (p. 204).
Subapennine marls and sands (p.
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Majority of the
Faluns of Touraine (p. 211).
Faluns, proper, of Bordeaux (p.
Fresh-water strata of Gers (p.
Swiss Oeningen beds, rich in plants and insects (pp. 215-23).
Marine Molasse, Switzerland (p.
Bolderberg beds of Belgium (p.
Vienna basin (p. 224).
Beds of the Superga, near Turin (p.
Deposit at Pikermé, near Athens (p. 226).
Strata of the Siwâlik hills, India (p. 226).
Marine strata of the Atlantic border in the United States (p. 227).
Volcanic tuff and limestone of Madeira, the Canaries, and the
Nearly all the
Hempstead beds, marine and fresh-water strata (p. 244).
Lignites and clays of Bovey Tracey (p. 245).
Isle of Mull leaf-bed, volcanic tuff (p. 247).
Calcaire de la Beauce, etc. (p.
Grès de Fontainebleau (p.
Lacustrine strata of the Limagne d’Auvergne, and the Cantal
Mayence basin (p. 242).
Radaboj beds of Croatia (p.
Brown coal of Germany (p.
Lower Molasse of Switzerland, fresh-water and brackish (p. 235-9).
Rupelmonde, Kleynspawen, and Tongrian beds of Belgium (p. 241, 242).
Nebraska beds, United States (p.
Lower Miocene beds of Italy (p.
Miocene flora of North Greenland (p.
Bembridge fluvio-marine strata (p.
Osborne or St. Helen’s series (p. 255).
Headon series, with marine and fresh-water shells (p. 255).
Barton sands and clays (p.
Gypsum of Montmartre, fresh-water with Palæotherium
Calcaire silicieux, or Travertin inférieur (p. 273),
Grès de Beauchamp, or Sables moyens (p. 273).
Bracklesham beds and Bagshot sands (p. 259).
White clays of Alum Bay and Bournemouth (p. 262).
Calcaire grossier, miliolitic limestone (p. 274).
Soissonnais sands, or Lits coquilliers, with Nummulites
planulata (p. 275).
Claiborne beds of the United States, with Orbitoides and
Zeuglodon (p. 279).
Nummulitic formation of Europe, Asia, etc. (p. 277).
London clay proper (p. 263).
Woolwich and Reading series, fluvio-marine (p. 267).
Thanet sands (p. 269).
Argile de Londres, near Dunkirk (p.
Argile plastique (p. 276).
Sables de Bracheux (p.
SECONDARY OR MESOZOIC.
Upper white chalk, with flints (p.
Lower white chalk, without flints (p. 298).
Chalk marl (p. 298).
Chloritic series (or Upper Greensand), fire-stone of Surrey (p. 298).
Gault (p. 300).
Blackdown beds (p. 301).
[ 134 ]
Maetricht beds and Faxoe chalk (p.
Pisolitic limestone of France (p.
White chalk of France, Sweden, and Russia (p. 286, 287).
Planer-kalk of Saxony (p.
Sands and clays of Aix-la-Chapelle (p. 302).
Hippurite limestone of South of France (p. 305).
New Jersey, U.S., sands and marls (p. 307).
Sands of Folkestone, Sandgate, and Hythe (p. 308).
Atherfield clay, with Perna mulleti (p. 309).
Punfield marine beds, with Vicarya lujana (p. 318).
Speeton clay of Flamborough Head and Tealby (p. 311).
Weald clay of Surrey, Kent, and Sussex, fresh-water, with
Cypris (p. 313-5).
Hastings sands (p. 316-8).
Neocomian of Neufchatel, and Hils conglomerate of North Germany
Wealden beds of Hanover (p.
Upper Purbeck beds, fresh-water (p.
Middle Purbeck, with numerous marsupial quadrupeds, etc. (p. 324).
Lower Purbeck, fresh-water, with intercalated dirt-bed (p. 330).
Portland stone and sand. (p.
Kimmeridge clay (p. 335).
Marnes à gryphées virgules of Argonne (p. 336).
Lithographic-stone of Solenhofen, with Archæopteryx
Coral rag of Berkshire, Wilts, and Yorkshire (p. 339).
Oxford clay, with belemnites and Ammonite (p. 340).
Kelloway rock of Wilts and Yorkshire (p. 341).
Nerinæan limestone of the Jura (p. 339).
Cornbrash and forest marble (p.
Great or Bath oolite of Bradford (p.
Stonesfield slate, with marsupials and Araucaria (p. 345).
Fuller’s earth of Bath (p.
Inferior oolite (p. 349).
|Upper Lias, argillaceous, with Ammonites
striatulus (p. 353).
Shale and limestone, with Ammonites bifrons (p. 353).
Middle Lias or Marlstone series, with zones containing
characteristic Ammonites (p.
Lower Lias, also with zones characterised by peculiar Ammonites
Rhætic, Penarth or Avicula contorta beds (beds of
passage) (p. 366).
Keuper or Upper New Red sandstone, etc. (p. 369).
Red shales of Cheshire and Lancashire, with rock-salt (p. 371).
Dolomite conglomerate of Bristol (p.
Keuper beds of Germany (p.
St. Cassian or Hallstadt beds, with rich marine fauna (p. 376).
Coal-field of Richmond, Virginia (p.
Chatham coal-field, North Carolina (p. 383).
Muschelkalk of Germany (p.
Bunter or Lower New Red sandstone of Lancashire and Cheshire (p. 372).
Bunter-sandstein of Germany (p.
Red sandstone of Connecticut Valley, with footprints of birds and
reptiles (p. 381).
[ 135 ]
PRIMARY OR PALÆOZOIC
Upper Permian of St. Bees’ Head, Cumberland (p. 386).
Middle Permian, magnesian limestone, and marl-slate of Durham and
Yorkshire, with Protosaurus (p. 387).
Lower Permian sandstones and breccias of Penrith and
Dumfriesshire, intercalated (p.
Dark-coloured shales of Thuringia (p. 392).
Zechstein or Dolomitic limestone (p.
Mergel-schiefer or Kupfer-schiefer (p. 392).
Rothliegendes of Thuringia, with Psaronius (p. 392).
Magnesian limestones, etc., of Russia (p. 393).
Coal-measures of South Wales, with underclays inclosing
Stigmaria (p. 397).
Coal-measures of north and central England (p. 395).
Millstone grit (p. 395).
Yoredale series of Yorkshire (p.
Coal-field of Kilkenny with Labyrinthodont (p. 407).
Coal-field of Saarbruck, with Archegosaurus (p. 406).
Carboniferous strata of South Joggins, Nova Scotia (p. 409).
Pennsylvania coal-field (p.
Mountain limestone of Wales and South of England (p. 430).
Same in Ireland (p. 437437).
Carboniferous limestone of Scotland alternating with coal-bearing
sandstones (p. 396).
Erect trees in volcanic ash in the Island of Arran (p. 546).
Mountain limestone of Belgium (p.
Yellow sandstone of Dura Den, with Holoptychius, etc. (p. 440); and of Ireland with
Anodon Jukesii (p.
Sandstones of Forfarshire and Perthshire, with
Holoptychius, etc. (p.
Pilton group of North Devon (p.
Petherwyn group of Cornwall, with Clymenia and
Cypridina (p. 451).
Clymenien-kalk and Cypridinen-schiefer of Germany (p. 450)
Bituminous schists of Gamrie, Caithness, etc., with numerous fish
Ilfracombe beds with peculiar trilobites and corals (p. 450).
Limestones of Torquay, with broad-winged Spirifers (p. 451).
Eifel limestone, with underlying schists containing
Calceola (p. 453).
Devonian strata of Russia (p.
Arbroath paving-stones, with Cephalaspis and
Pterygotus (p. 446).
Lower sandstones of Forfarshire, with Pterygotus (p. 446).
Sandstones and slates of the Foreland and Linton (p. 454).
Oriskany sandstone of Western Canada and New York (p. 456).
Sandstones of Gaspe, with Cephalaspis (p. 455 ).
[ 136 ]
Upper Ludlow formation, Downton sandstone, with bone-bed (p. 459).
Lower Ludlow formation, with oldest known fish remains (p. 461).
Wenlock limestone and shale (p.
Woolhope limestone and grit (p.
Tarannon shales (p. 468).
Beds of passage between Upper and Lower Silurian:
Upper Llandovery, or May-hill sandstone, with Pentamerus
oblongus, etc. (p. 468).
Lower Llandovery slates (p.
Niagara limestone, with Calymene, Homalonotus, etc. (p. 479).
Clinton group of America, with Pentamerus oblongus, etc.
Silurian strata of Russia, with Pentamerus (p. 477).
Bala and Caradoc beds (p.
Llandeilo flags (p. 473).
Arenig or Stiper-stones group (Lower Llandeilo of Murchison) (p. 475).
Ungulite or Obolus grit of Russia (p. 477).
Trenton limestone, and other Lower Silurian groups of North
America (p. 479).
Lower Silurian of Sweden (p.
Tremadoc slates (p. 483).
Lingula flags, with Lingula Davisii (p. 484).
"Primordial" zone of Bohemia in part, with trilobites of the
genera Paradoxides, etc. (p.
Alum schists of Sweden and Norway (p. 489).
Potsdam sandstone, with Dikelocephalus and Obolella
Menevian beds of Wales, with Paradoxides Davidis, etc. (p. 484).
Longmynd group, comprising the Harlech grits and Llanberis slates
Lower portion of Barrande’s "Primordial" zone in Bohemia
Fucoid sandstones of Sweden (p.
Huronian series of Canada? (p.
Fundamental gneiss of the Hebrides? (p. 493).
Hypersthene rocks of Skye? (p.
Labradorite series north of the river St. Lawrence in Canada (p. 491).
Adirondack mountains of New York (p.
Beds of gneiss and quartzite, with interstratified limestones, in
one of which, 1000 feet thick, occurs a foraminifer, Eozoon
Canadense, the oldest known fossil (p. 491).