THE lower portion of Plate 1, is an imaginary section, constructed to express by the insertion of names and colours, the relative positions of the most important classes both of unstratified and stratified rocks, as far as they have yet been ascertained.

The merit of this section is due to the talents of Mr. Thomas Webster; it has been enlarged and improved by him from an original section, which he has for several years exhibited in illustration of his lectures; it was in tended to illustrate a work on Geology, which he is preparing for the press, and he has liberally permitted me to use it likewise in the present work, with some few additions and alterations of my own.

This Section exhibits under one point of view the relations of the Granitic and Volcanic rocks to the stratified formations, and to one another, more intelligibly than I have ever seen expressed elsewhere. The selection and arrangement of the animals and plants in the upper part of this Plate is exclusively my own; these have been drawn and engraved (together with a large proportion of the wood cuts) by Mr.. J. Fisher, of St. Clements, Oxford.

The section is founded on many series of accurate observations, on several lines taken across Europe, between the British islands and the Mediterranean Sea. Although no single straight line exhibits every formation complete in the [002] full order of succession here represented, no fact is inserted for which authority cannot be found. The near approximation of this synoptic representation by Mr. Webster to the facts exhibited by an actual section, may be estimated by comparing it with the admirable section across Europe, published by Mr. Conybeare in the Report of the Proceedings of the British Association for the Advancement of Science 1832, and with his sections of England, in Phillips and Conybeare's Geology of England and Wales.

For facility of reference, I have numbered the principal groups of stratified rocks represented in the section, according to their most usual order of succession; and have designated by letters the crystalline or unstratified rocks, and the injected masses and dykes, as well as the metallic veins, and lines of fracture, producing dislocations or faults. The crowded condition in which all the Phenomena represented in this section, are set together, does not admit of the use of accurate relative proportions between the stratified rocks, and the intruded masses, veins, and dykes by which they are intersected. The adoption of false proportions is, however, unavoidable in these cases, because the veins and dykes would be invisible, unless expressed on a highly exaggerated scale. The scale of height throughout the whole section is also infinitely greater than that of breadth. The plants and animals also are figured on no uniform scale.

The extent of the different formations represented in this section, taking their average width as they occur in Europe, would occupy a breadth of five or six hundred miles. A scale of heights, at all approaching to this scale of breadth, would render the whole almost invisible. The same cause makes it also impossible to express correctly the effect of vallies of denudation, which are often excavated through strata of one formation into those of another subjacent formation. [003] As it would encumber the section to express Diluvium, wherever it is present, it is introduced in one place only, which shews its age to be more recent than the newest of the Tertiary strata; it is found also lodged indiscriminately upon the surface of rocks of every formation.

In our early Chapters we have considered the Theory which refers unstratified rocks to an igneous Origin, to be that which is most consistent with all the known Phenomena of Geology, and the facts represented in the Section now before us are more consistent with the Postulates of this Hypothesis, than with those of any other that has hitherto been proposed. I have, therefore, felt it indispensable to adopt its language, as affording the only terms by which the facts under consideration can be adequately described.

Assuming that Fire and Water have been the two great Agents employed in reducing the surface of the globe to its actual condition, we see, in repeated operations of these agents, causes adequate to the production of those irregular Elevations and Depressions of the fundamental Rocks of the Granitic series, which are delineated in the lower Region of our Section, as forming the basis of the entire Superstructure of stratified Rocks.

Near the right extremity of this Section, the undulating surface of the fundamental Granite (a. 5. a. 6. a. 7. a. 8.) is represented as being, for the most part, beneath the level of the Sea.

On the left extremity of the Section (a. l. a. 2. a. 3.) the Granite is elevated into one of those lofty Alpine ridges, which have affected, by their upward movement, the entire series of stratified Rocks.

Corresponding formations of Primary and Transition [004] Strata, are represented as occurring on each side of this elevated Granite, which is supposed to have broken through, and to have carried up with it to their present elevated and highly inclined position, strata that were once continuous and nearly horizontal.*

The general history of Elevation appears to be, that mountain chains of various extent, and various directions, have been formed at irregular intervals, during the deposition of stratified rocks of every age ; and that Granite had, in many cases, acquired a state of solidity before the period of its elevation.

Within the primary Granite, we find other forms of Granitic matter, (a. 9.) which appear to have been intruded in a state of fusion, not only into fissures of the older Granite, but frequently also into the Primary stratified rocks in contact with it, and occasionally into strata of the Transition and Secondary series, (a. 10. a. 11.) these Granitic injections were probably in many cases, contemporaneous with the elevation of the rocks they intersect; they usually assume the Condition of Veins, terminating upwards in small branches; and vary in dimensions, from less than an inch, to an indefinite width. The direction of these veins is very irregular: they sometimes traverse the Primary strata at right angles to their planes of stratification, at other times they are protruded in a direction parallel to these planes, and assume the form of beds. Some of the relations of these Granitic Veins to the rocks intersected by them are represented at the left extremity of the Section. (a. 9.) 

* Cases of Granite, thus elevated at a period posterior to the deposition of Tertiary Strata, occur in the Eastern Alps, where the Transition, Secondary, and Tertiary strata have all partaken of the same elevation which raised the central axis of the crystalline Granitic rocks. See Geol. Trans. N. S. Vol. III. PL. 36. Fig. l.

In the Granite at the right extremity of the Section, the granitic veins are omitted, because their insertion would interfere with

[005] A. 10. represents a dyke and protruded mass of Granite, intersecting and overlying stratified rocks of the Primary and Transition series. A. 11. represents the rare case of Granite intersecting Red Sandstone, Oolite, and Chalk.*

Closely allied to Granitic Veins, is a second series of irregularly injected rocks, composed of Sienite, Porphyry, Serpentine, and Green Stone (b. c. d. e.) which traverse the Primary and Transition formations, and the lower regions of the Secondary strata; not only intersecting them in various directions, but often forming also overlying masses, in places where these veins have terminated by overflowing at the surface, b'. c'. d'. e'.) The crystalline rocks of this series, present so many modifications of their ingredients, that numerous varieties of Sienite, Porphyry, and Greenstone occur frequently in the products of Eruptions from a single vent.

The scale of our Section admits not of an accurate representation of the relations between many of these intruded rocks, and the strata they intersect; they are all placed, as

the represciitation of the injections of Basaltic and Volcanic matter which that portion of the section is intended to illustrate.

* An example of the rare Phenomenon of Granite intruded into the Chalk formation, in the hill of St. Martin, near Pont de la Fou in the Pyrenees, is described by M. Dufrenoy in the Bulletin de la Société Géologique de France, Tom. 2. page 73.

At Weinböhla, near Meissen in Saxony, Prof. Weiss has ascertained the presence of Sienite above strata of Chalk; and Prof. Nauman states, that, near Oberau, Cretaceous rocks are covered by Granite, and that near Zscheila and Neiderfehre, the Cretaceous rocks rest horizontally on Granite ; at both these places the Limestone and Granite are entangled in each other, and irregular portions and veins of hard Limestone, with green grains and cretaceous fossils, are here arid there imbedded in the Granite.

Examples of the fractures and dislocations attending these movements, and producing faults, are represented in our Section by the lines designated by the letter l. Some of these fractures do not reach to the present surface, as they affected the lower beds at periods anterior to the deposition of more recent strata, which cover unconformably the summits of the earlier fractures. (See l. 1¹. l². 1⁵. 1⁶. 1⁷.)

A third series of Igneous Rocks is that which has formed dykes, and masses of Basalt and Trap, intruded into, and overlying formations of all ages, from the earliest Granites to the most recent Tertiary Strata. These basaltic rocks sometimes occur as Beds, nearly parallel to the strata, into which they are protruded, after the manner represented in the carboniferous Limestone of our Section, f. 2. More frequently they overspread the surface like expanded sheets of Lava. Our Section gives examples of Trap under all these circumstances. At f. l. it intersects and overlies Primary strata; at f. 2. f. 3. f. 4. f. 5. it stands in similar [007] relations to Transition and Secondary strata; f. 6. represents an example of an extensive eruption of Basaltic matter, over Chalk and Tertiary strata, accompanied by an intrusion of vast irregular masses of the same materials into the body of the subjacent Primary and Transition rocks.

f. 7. represents strata of columnar Basalt, immediately beneath streams of cellular Lava, in regions occupied also by craters of extinct Volcanos. f. 8. represents similar beds of columnar lava in the vicinity of active Volcanos.

The fourth and last class of intruded rocks, is that of modern volcanic Porphyries, Trachytes,* and Lavas. The undeniable igneous origin of rocks of this class forms the strongest ground-work of our arguments, in favour of the igneous formation of the older unstratified and crystalline rocks; and their varied recent products, around the craters of active Volcanos, present graduations of structure, and composition, which connect them with the most ancient Porphyries, Sienites, and Granites.

The simplest cases of volcanic action are those of Trachyte (g. 1.) and of Lava (i. 5.) ejected through apertures in Granite; such cases prove that the source of volcanic fires, is wholly unconnected with the pseudo-volcanic results of the combustion of coal, bitumen, or sulphur, in stratified formations, and is seated deep beneath the Primary rocks.

* The appellation of Trachyte has been given to a volcanic Porphyry, usually containing Crystals of glassy felspar, and remarkably harsh to the touch, (hence its name from ); it does not occur in Britain, but abounds in the neighbourhood of almost all extinct and active volcanic craters.

The occurrence of angular fragments of altered Granite, embedded in Pillars of columnar Lava, in the valley of Monpezat in the Ardêche, shews that these fragments were probably torn off during

[008]

Our section represents three cases of Volcanic craters; the most simple (i. 5.) rising through Granite, or stratified rocks, at the bottom of the sea, and accumulating craters, which, like those of Lipari and Stromboli, Sabrina, and Graham Islands, are occasionally formed in various parts of the ocean.* The second case is that of volcanos, which, like Etna and Vesuvius, are still in action on the dry land, (i. l. to i. 4.) The third is that of extinct volcanos, like those in Auvergne, (h¹. h².) which, although there exist no historical records as to the period of their last eruptions, shew by the perfect condition of their craters, that they have been formed since the latest of those aqueous inundations, that have affected the Basalts and Tertiary strata, through which they have burst forth.

One great difference between the more ancient Basaltic eruptions and those of the Lava and Trachyte of existing volcanos, is that the emission of the former, probably taking place under the pressure of deep water, was not accompanied by the formation of any permanent craters.

In both cases, the fissures through some of which these Eruptions may have issued, are abundantly apparent under

the upward passage of the Lava through fractures in the solid Granite.

At Graveneire, near Clermont, a stream of Lava still retains the exact form, in which it issued through a fissure in the side of a mountain of Granite, and overflowed the subjacent valley. Most accurate representations of this, and many similar productions of Volcanic Eruptions from the Granite of this District may be seen in Mr. Poulett Scrope's inimitable Panoramic Views of the Volcanic formations of Central France.

* Within the last few years, the Volcanic Cones of Sabrina in the Atlantic, and of Graham Island in the Mediterranean, have risen suddenly in the sea and been soon levelled and dispersed by the Waves.

[009] the form of Dykes, filled with materials similar to those which form the masses that have overflowed in the Vicinity of each Dyke.*

The peculiar condition of the rocks that form the side walls of Granitic Veins and Basaltic Dykes, affords another argument in favour of their igneous origin; thus wherever the early Slate rocks are intersected by Granitic Veins (a. 8.) they are usually altered to a state approximating to that of fine-grained Mica-Slate, Hornblende-Slate.

The Secondary and Tertiary rocks also, when they are intersected by basaltic Dykes, have frequently undergone some change; beds of Shale and Sandstone are indurated, and reduced to Jasper; compact Limestone and Chalk are converted to crystalline Marble, and Chalk-flints altered to a state like that resulting from heat in an artificial fur nace.

In all these cases, the Phenomena appear to be throughout consistent with the theory of igneous Injection, and to be incapable of explanation on any other Hypothesis that has been proposed. A summary statement of the probable relations of the Granitic and Trappean Rocks to the other materials of the Globe, and to one another, may be found in De la Beche's Geological Researches, 1st Edit. Pag. 374, et seq.

* In many dykes the materials have been variously modified, by their mode of cooling, and differ from the masses which overflowed the surface.

Examples of this kind occur on the sides of Basaltic Dykes in tersecting Chalk in the County of Antriin, and in the Island of Raghlin. See Geol. Trans. London, 0. S. vol. iii. p. 210. Pl. 10.

[010]

a. Granite. b. Sienite. c. Porphyry.
d. Greenstone. e. Serpentine. f. Basalt, or Trap.
g. Trachyte. h. Products of Extinct Volcanos.
i. Products of Active Volcanos.

a. 1.-a. 3. Mountains of Granite, raised into lofty ridges, from beneath Gneiss and Primary Slates.
a. 4. Granite intermixed with Gneiss.
a. 5.-a. 8. Granite, subjacent to stratified rocks of all ages, and intersected by volcanic rocks.
a. 9. Granite Veins, intersecting Granite, Gneiss, and primary Slate.
a. 10. Granite Vein, intersecting Primary and Transition rocks, and forming overlying masses at the surface.
a. 11. Granite Vein, intersecting Secondary strata, and overlying Chalk.*

b. Dykes of Sienite.
b. l. Overlying masses of Sienite.

c. Dykes of Porphyry.
c. l. Overlying masses of Porphyry.

d. Dykes of ancient Greenstone.
d. l. Overlying masses of the same. The Rocks represented by d. and e. often pass into one another.

e. Dykes of Serpentine.
e. 1. Overlying masses of Serpentine.

f. Dykes and intruded subterraneous masses of Basalt.
f. l. to f. 7. Masses of Basalt protruded through, and overlying strata of various ages.
f. 8. Basaltiform products of Modern Volcanos.

* In the locality quoted in the Explanation of Plates, Vol. II. p. 5 [005 above, note *  - ed.], the Granite which comes to the surface over the Chalk, is not covered by Tertiary deposits, as represented in our section, PL. l.

[011]

g. Trachyte forming Dykes.
g. l. Trachyte forming overlying Domes. (Puyde Dome.)

h. l. h. 2. Lava of extinct Volcanos, forming undisturbed Cones. (Auvergne.)

i.-i. 5. Lava, Scoriæ, and Craters of active Volcanos.
      (i. 1.-i. 4. Etna. i.-5. Stromboli.)

k.-k. 24. Metalliferous Veins.
k. 15'. Lateral expansions of Veins into metalliferous cavities, called by the Miners Pipe Veins, or Flats.

l.-l. 7. Faults, or fractures and dislocations of the strata. The continuity of stratified Rocks is always interrupted, and their level more or less changed on the opposite sides of a fault.

It is unnecessary here to give detailed descriptions of the 28 divisions of the Stratified formations represented in our Section. Their usual Order of Succession and Names are expressed in their respective places, and detailed descriptions of their several characters may be found in all good Treatises on Geology.

The leading Groups of these Formations are united by colours, marking their separation from the adjacent groups; and the same colours are repeated, in the headings above the figures of Plants and Animals, that characterize the several series of Formations, to show the extent of the strata over which the Organic Remains of each Group are respectively distributed.

Although the deposits of Peat Bogs, and Calcareous Tufa are of too local a nature to be generally included in the series of stratified Rocks, they are represented in this Section (Figs. 31, 32), because they sometimes operate locally to a considerable extent in adding permanent and solid matter to the surface of the Globe.

[012]

List of the Names of the Plants and Animals, represented in PL. l. to denote the prevailing Types of Vegetable and Animal Lffe, during the formation of the divisions of stratified Rocks.

r. recent.  f.fossil. Ad. B. Adolphe Brongniart. Ag. Agassiz. P. Page ofVol. l.

l. Araucaria. Norfolk Island Pine. r.&f. P. 484.
2. Equisetum. r. & f. P. 460.
3. Calamites nodosus. f. (L. Pl. 16.)
4. Asterophillites comosa. f. (L. 108.)
5. Asterophillites foliosa. f. (L. 25.)
6. Aspidium. r. Pecopteris. f.
7. Cyathea glauca, Tree Fern. r. (Ad. B. Hist. Veg. Foss. PL. 38.) P. 464.
8. Osmunda. r. Neuropteris. f.
9. Lycopodium cernuum. r.
10. Lycopodium alopecuroides. r. (from Mirbel.) P. 466.
11. Lepidodendron Sternbergii. f.
12. Lepidodendron gracile? f.
13. Flabelliform Palm. r. (from Mirbel.) Palmacites. f.

14. Acanthodes. f. Ag.
15. Catopterus. f. Ag.
16. Amblypterus. f. Ag.
17. Orodus, extinct Shark. f. (Imaginary restoration).
[013]
18. Cestracion Phillippi, Port Jackson Shark. r. (Phillip.) P. 288.
18'. Palatal Tooth of Cestracion Phillippi. r.
19. Tooth of Psammodus, from Derbyshire limestone. f.
19'. Tooth of Orodus, from Mountain limestone, near Bristol. f.

Trilobites. P. 391.:
   20. Calymene. f.
   21. Paradoxus. f.
   22. Asaphus. f.

23. Euomphalus. f.
24. Producta. f.
25. Spirifer. f.
26. Actinocrinites. f. (Miller, P. 96.) P. 417.
27. Platycrinites. f. (Miller, P. 74.)
27^a. Fucoides circinatus. f. (Ad. B.) From Transition sandstone, Sweden.
28. Caryophyllia. r. & f.
29. Astrea. r. & f.
30. Turbinolia. r. & f.

* This shark is the only known living representative of the extinct genus Psammodus.
Fig. 27. In most, if not all the species of Platycrinites the arms are subdivided; they are not so in this figure, as from its small size they could not well be represented. The figure is intended to give only a general idea of the subject.

[014]

39. Scolopendrium r. Tæniopteris in Oolite. Scarborough. f.

40. Didelphys. r. Stonesfield slate, 2 small species.
41. Didelphys. r. Cheirotherium? f. P. 265.
42. Pterodactylus brevirostris. f.
43. Pterodactylus crassirostris. f.
44. Gavial. r. Allied to Teleosaurus.
45. Iguana. r. Iguanodon. f.
46. Testudo, Land Tortoise. r. Scales of Tortoises, at
Stonesfield,Oxon. f. Footsteps of Tortoises, Dumfries. f.
47. Emys. r. Soleure. f.
48. Buprestis. r. Stonesfield. f.
49. Libellula. r. Solenhofen. f.

50. Plesiosaurus. f.
51. Ichthyosaurus. f.
52. Marine Turtle. r. At Luneville, in Muschel Kalk. f. P. 256.
53. Pygopterus. f. (Ag. Vol. l. PL. D. 3.) in Magnesian Limestone.
54. Dapedium, in Lias. f.
55. Hybodus. f. Extinct genus of Sharks. Imaginary restoration.)
56. Loligo. r. Lyme Regis. f.
57. Nautilus Pompilius. r. Many species. f.
58. Ammonites Bucklandi. f. Peculiar to Lias.
59. Astacus. r. & f.
60. Limulus, King Crab. r. Solenhofen. f.
61. Trigonia. f. New Holland. r.
62. Ophiura. r.&f.
63. Asterias. r.&f.

[015]
64. Echinus. r.&f.
65. Apiocrinites. f.
65^a. Fucoides recurvus. f. (Ad. B. Hist. Veg. Foss. Pl. 5. Fig. 2.)

66. Mauritia aculeata. r. (Martius, T. 44.) Palmacites. Lamanonis. f.
 P. 214.
67. Elaeis guineensis. r. (Martius, T. 56.) Fruits of Pinnate Palms. f. P. 515.
68. Cocos nucifera. r. (Martius, Pl. 62.)  Fossil Cocoa nut, Sheppy, Brussels. P. 515.
69. Pinus, Pine. r. & f.
70. Ulmus, Elm. r. & f.
71. Populus, Poplar. r. & f.
72. Salix, Willow. r. & f.

73. Scolopax, Woodcock. r. & f.
74. Ibis. r. & f.
75. Tringa, Sea Lark.  r. & f.
76. Coturnix, Quail.  r. & f.
77. Strix, Owl. r. & f.
78. Buteo, Buzzard. r. & f.
79. Phalacrocorax, Cormorant.  r. Pelecanus. f.

80. Emys, Fresh water Tortoise.
81. Trionyx, Soft Tortoise. r. & f.
82. Crocodilus, Crocodile. r. & f.

83. Vespertilio, Bat. r. & f.
84. Sciurus, Squirrel. r. & f.
85. Myoxus, Dormouse. r. & f.

[016]

86. Castor, Beaver. r. & f.
87. Genetta, Genet. r. & f.
88. Nasua, Coati. r. & f.
89. Procyon, Racoon. r. & f.
90. Canis Vulpes, Fox. r. & f.
91. Canis Lupus, Wolf. r. & f.
92. Didelphys, Opossum, small. r. & f.
93. Anoplotherium commune. f.
94. Anoplotherium gracile. f.
95. Palæotherium magnum. f.
96. Palæotherium minus. f.

Genera of Shells most characteristic of the Tertiary Periods . . .

a. Planorbis. r. & f. b. Limnæa. r. & f. c. Conus. r. & f. d. Bulla. r. & f.  e. Cypræa. r. & f.  f. Ampullaria. r. & f. g. Scalaria. r. & f. h. Cerithium. r. & f. i. Cassis. r. & f. j. Pyrula. r. & f. k. Fusus. r. & f. l. Voluta. r & f. m. Buccinum. r. & f.  n. Rostellaria. r. & f.

97. Phoca, Seal. r. & f.
98. Trichechus, Walrus. r. & f.
99. Deiphinus Orca, (Phocœna, Cuv.) Grampus. r. Delphinus. f
100. Manatus, Lamantin. r. & f.
101. Balæna, Whale. r. & f.

[017]

120. Didus, Dodo. r. & f.

The bones of the Dodo have been found under lava of unknown age in the Isle of France, and in a cavern in the Island of Roderigue. See Zoological Journal, 1828, p. 554. Loudon's Mag. Nat. Hist. Vol. IL p. 442. and London and Edin. Phil. Mag. Dec. 1832.

* Many of the following genera occur both in the second, third and fourth formations of the Tertiary series, and also in Caverns, Fissures, and Diluvium.