Chapter II

The Old Red Sandstone.--Till very lately its Existence as a
distinct Formation disputed.--Still little known.--Its great
Importance in the Geological Scale.--Illustration.--The
North of Scotland girdled by an immense Belt of Old Red
Sandstone.--Line of the Girdle along the Coast.--Marks of vast
Denudation.--Its Extent partially indicated by Hills on the
western Coast of Ross-shire.--The System of great Depth in the
North of Scotland.--Difficulties in the Way of estimating the
Thickness of Deposits.--Peculiar Formation of Hill.--Illustrated
by Ben Nevis.--Caution to the Geological Critic.--Lower Old
Red Sandstone immensely developed in Caithness.--Sketch
of the Geology of that County.--Its strange Group of
Fossils.--their present Place of Sepulture.--Their ancient
Habitat.--Agassiz.--Amazing Progress of Fossil Ichthyology during
the last few Years.--Its Nomenclature.--Learned Names repel
unlearned Readers.--Not a great deal in them, 15-34

CHAPTER III.

Lamarck's Theory of Progression illustrated.--Class of Facts
which give Color to it.--The Credulity of _Unbelief_.--M.
Maillet and his Fish-birds.--Gradation not Progress.--Geological
Argument.--The Present incomplete without the Past.--Intermediate
Links of Creation.--Organisms of the Lower Old Red
Sandstone.--The _Pterichthys_.--Its first Discovery.--Mr.
Murchison's Decision regarding it.--Confirmed by that of
Agassiz.--Description.--The several Varieties of the Fossil
yet discovered.--Evidence of violent Death in the Attitudes
in which they are found.--The Coccosteus of the Lower Old
Red.--Description.--Gradations from Crustacea to Fishes.--Habits
of the _Coccosteus_.--Scarcely any Conception too extravagant for
Nature to realize, 35-54

CHAPTER IV.

The Elfin-fish of Gawin Douglas.--The Fish of the Old Red
Sandstone scarcely less curious.--Place which they occupied
indicated in the present Creation by a mere Gap.--Fish divided
into two great Series, the Osseous and Cartilaginous.--Their
distinctive Peculiarities.--Geological Illustration of
Dr. Johnson's shrewd Objection to the Theory of Soame
Jenyns.--Proofs of the intermediate Character of the
Ichthyolites of the Old lied Sandstone.--Appearances which
first led the Writer to deem it intermediate.--Confirmation by
Agassiz.--The _Osteolepis_.--Order to which, this Ichthyolite
belonged.--Description.--_Dipterus._--_Diplopierus._--
_Cheirolepis._--_Glyptolepis_, 55-78

CHAPTER V.

The Classifying Principle and its Uses.--Three Groups
of Ichthyolites among the Organisms of the Lower Old
Red Sandstone.--Peculiarities of the Third Group.--Its
Varieties.--Description of the _Cheiracanthus_.--Of two unnamed
Fossils of the same Order.--Microscopic Beauty of these
ancient Fish.--Various Styles of Ornament which obtain among
them.--The Molluscs of the Formation.--Remarkable chiefly for
the Union of modern with ancient Forms which they exhibit.--Its
Vegetables.--Importance and Interest of the Record which it
furnishes, 79-94

CHAPTER VI.

The Lines of the Geographer rarely right Lines.--These last,
however, always worth looking at when they occur.--Striking
Instance in the Line of the Great Caledonian Valley.--Indicative
of the Direction in which the Volcanic Agencies have
operated.--Sections of the Old Red Sandstone furnished by the
granitic Eminences of the Line.--Illustration.--Lias of the Moray
Frith.--Surmisings regarding its original Extent.--These lead to
an exploratory Ramble.--Narrative.--Phenomena exhibited in the
Course of half an Hour's Walk.--The little Bay.--Its Strata and
their Organisms, 95-108

CHAPTER VII.

Further Discoveries of the Ichthyolite Beds.--Found in one
Locality under a Bed of Peat.--Discovered in another beneath
an ancient Burying-ground.--In a third underlying the Lias
Formation.--In a fourth overtopped by a still older Sandstone
Deposit.--Difficulties in ascertaining the true Place of a
newly-discovered Formation.--Caution against drawing too hasty
Inferences from the mere Circumstance of Neighborhood.--The
Writer receives his first Assistance from without.--_Geological
Appendix_ of the Messrs. Anderson, of Inverness.--Further
Assistance from the Researches of Agassiz.--Suggestion.--Dr.
John Malcolmson.--His extensive Discoveries in Moray.--He
submits to Agassiz a Drawing of the _Pterichthys_.--Place of the
Ichthyolites in the Scale at length determined.--Two distinct
Platforms of Being in the Formation to which they belong, 109-124

CHAPTER VIII.

Upper Formations of the Old Red Sandstone.--Room enough, for each
and to spare.--Middle, or Cornstone Formation.--The Cephalaspis
its most characteristic Organism.--Description.--The Den of
Balruddery richer in the Fossils of this middle Formation than
any other Locality yet discovered.--Various Contemporaries
of the _Cephalaspis._--Vegetable Impressions.--Gigantic
Crustacean.--_Seraphim._--Ichthyodorulites.--Sketch of the
Geology of Forfarshire.--Its older Deposits of the Cornstone
Formation.--The Quarries of Carmylie.--Their Vegetable and Animal
Remains.--The Upper Formation.--Wide Extent of the Fauna and
Flora of the earlier Formations.--Probable Cause, 125-150

CHAPTER IX.

Fossils of the Upper Old Red Sandstone much more imperfectly
preserved than those of the Lower.--The Causes
obvious.--Difference between the two Groups, which first strikes
the Observer, a difference in size.--The _Holoptychius_ a
characteristic Ichthyolite of the Formation.--Description of its
huge Scales.--Of its Occipital Bones, Fins, Teeth, and general
Appearance.--Contemporaries of the _Holoptychius_.--Sponge-like
Bodies.--Plates resembling those of the Sturgeon.--Teeth of
various forms, but all evidently the teeth of fishes.--Limestone
Band and its probable Origin.--Fossils of the Yellow
Sandstone.--the _Pterichthys_ of Dura Den.--Member of a Family
peculiarly characteristic of the System.--No intervening
Formation between the Old Red Sandstone and the Coal
Measures.--The _Holoptychius_ contemporary for a time with the
_Megalichthys_,--The Columns of Tubal-Cain, 151-172

CHAPTER X.

Speculations in the Old Red Sandstone, and their
Character.--George, first Earl of Cromarty.--His Sagacity as
a Naturalist at fault in one instance.--Sets himself to dig
for Coal in the Lower Old Red Sandstone.--Discovers a fine
Artesian Well.--Value of Geological Knowledge in an economic
view.--Scarce a Secondary Formation in the Kingdom in which
Coal has not been sought for.--Mineral Springs of the Old
Red Sandstone.--Strathpeffer.--Its Peculiarities whence
derived.--Chalybeate Springs of Easter Ross and the Black
Isle.--Petrifying Springs.--Building-Stone and Lime of the Old
Red Sandstone.--Its various Soils, 173-189

CHAPTER XI.

Geological Physiognomy.--Scenery of the Primary Formations;
Gneiss, Mica Schist, Quartz Rock.--Of the Secondary; the
Chalk Formations, the Oolite, the New Red Sandstone, the Coal
Measures.--Scenery in the Neighborhood of Edinburgh.--Aspect
of the Trap Rocks.--The Disturbing and Denuding
Agencies.--Distinctive Features of the Old Red Sandstone.--Of
the Great Conglomerate.--Of the Ichthyolite Beds.--The Burn of
Eathie.--The Upper Old Red Sandstones.--Scene in Moray, 190-210

CHAPTER XII.

The two Aspects in which Matter can be viewed; Space and
Time.--Geological History of the Earlier Periods.--The Cambrian
System.--Its Annelids.--The Silurian System.--Its Corals,
Encrinites, Molluscs, and Trilobites.--Its Fish.--These
of a high Order, and called into Existence apparently by
Myriads.--Opening Scene in the History of the Old Red Sandstone
a Scene of Tempest.--Represented by the Great Conglomerate.--Red
a prevailing Color among the Ancient Rocks contained in this
Deposit.--Amazing Abundance of Animal Life.--Exemplified by a
Scene in the Herring Fishery.--Platform of Death.--Probable Cause
of the Catastrophe which rendered it such, 211-225

CHAPTER XIII.

Successors of the exterminated Tribes.--The Gap slowly
filled.--Proof that the Vegetation of a Formation may long
survive its Animal Tribes.--Probable Cause.--Immensely extended
Period during which Fishes were the Master-existences of our
Planet.--Extreme Folly of an Infidel Objection illustrated
by the Fact.--Singular Analogy between the History of Fishes
as Individuals and as a Class.--Chemistry of the Lower
Formation.--Principles on which the Fish-enclosing Nodules were
probably formed.--Chemical Effect of Animal Matter in discharging
the Color from Red Sandstone.--Origin of the prevailing tint
to which the System owes its Name.--Successive Modes in which
a Metal may exist.--The Restorations of the Geologist void of
Color.--Very different Appearance of the Ichthyolites of Cromarty
and Moray, 226-242

CHAPTER XIV.

The Cornstone Formation and its Organisms.--Dwarf
Vegetation.--_Cephalaspides._--Huge Lobster.--Habitats of
the existing Crustacea.--No unapt representation of the
Deposit of Balruddery, furnished by a land-locked Bay in the
neighborhood of Cromarty.--Vast Space occupied by the Geological
Formations.--Contrasted with the half-formed Deposits which
represent the existing Creation.--Inference.--The formation
of the _Holoptychius_.--Probable origin of its Siliceous
Limestone.--Marked increase in the Bulk of the Existences of the
System.--Conjectural Cause.--The Coal Measures.--The Limestone of
Burdie House Conclusion, 243-259

Ichthyolites of the Old Red Sandstone--from Agassiz's "Poissons
Fossiles," 261-288

EXPLANATIONS OF THE SECTIONS AND PLATES.