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MEMOIRS

OF THE

WERNERIAN NATURAL HISTORY SOCIETY,

FOR THE YEARS 1831-37.

VOL. VII.

COMPRISING,

I. MR CUNNINGHAWM’S PRIZE ESSAY ON THE GEOLOGY OF THE LOTHIANS, wirn Tuirty-rivE CoLourzEp S£cTIONs, AND A GEOLOGICAL Mar oF THE LOTHIANS.

If. DR PARNELL’S PRIZE ESSAY ON THE FISHES OF THE DISTRICT OF THE FORTH, wirs Sixty-seven ILLusTRATIVE FiGures.

Ill. HISTORY OF THE SOCIETY rrom Decemper 183] tTrLu APRIL 1838,

EDINBURGH:

ADAM AND CHARLES BLACK ;

AND LONGMAN, ORME, BROWN, GREEN & LONGMANS, LONDON.

MDCCCXXXVIII.

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A NE gp IGE ATTA

CONTENTS.

On THE GeoLogy oF THE LoTHtans.' By RoBertT JAMES Hay Cunninenam, Esq.

Introductory Remarks, . . : Page 3 General Account of the Lothians, . : : rs «Transition Rocks, ' : i é P 8 Secondary Rocks, _.. - ; hi he Junction of the Transition and Secondary, . BOSS. Felspathic Rocks, ; , , : 2. 88 Augitic or Trap Rocks, : : : . 40 Ignigenous Rocks, . ‘ . : ne 47 Connexions of Neptunian and Plutonian Rocks, a. 48

Topographical descriptions of Salisbury Craigs, Arthur's Seat, Calton Hill, Castle Rock, the Pentlands, &c.

&e. A : : ; 51, 110 Alluvial Rocks, : : ‘ ee Physiognomy of the Loa : : a Observations on the Geology of Fife, : « 128 Sir James Hall’s experiments on rocks of the Lothians,

&e. : : d ‘ : “236 On the Junction of Greywacke and Sandstone with

Granite and Syenite, : . 146

Explanation of Geological Map of Siihians and of Plates, 3 : ; A ; a OS

1V CONTENTS.

ON THE NATURAL AND EconomicaL History OF THE FIsHEs oF THE River DIstTRICT OF THE FRITH OF Forty. By Ricnarp PARNELL, M. D.

Description of the Frith of Forth, — . ; : 161 OssEous FISHEs.

Order I. Acanthopterygii, ; : ; 167

II. Malacopterygii, : 5 -.. 266

III. Osteodermi, , : : ; 394

IV. Gymnodontes, : : : 401 CARTILAGINOUS FIsHEs.

Order J. Eleutheropomi, . 3 ; : 403

II. Plagiostomi, : : : é 407

III. Cyclostomi, : : . : 442

APPENDIX. 2

History of the Society (continued from Vol. V1.) : 461

MEMOIRS

OF THE

WERNERIAN NATURAL HISTORY SOCIETY.

VOL, VII. A

a - - xe hy

nt

ON THE

GEOLOGY OF THE LOTHIANS.* BY

ROBERT JAMES HAY CUNNINGHAM, Eso. M. W.S.

INTRODUCTORY REMARKS.

In offering this essay to the consideration of the Wernerian Natural History Society, the author considers that, for the satisfaction of those to whose scrutiny it is submitted, he is called upon to state some of the circumstances attending its production. The necessary investigations were com- menced in the beginning of the summer of the year 1834, and continued with little interruption till the middle of July, after which they were suspended till March 1835 ; and since that period, up to this date, few weeks have elapsed without more or less time being spent in examination. ‘The deficiencies of the essay, therefore, whatever these may be, cannot be referred to its hasty formation ; and if its short-

ness be considered as hardly agreeing with these state-

* The Wernerian Natural History Society’s Honorary Premium of Twenty Sovereigns was adjudged to Mr Cunningham for this Essay.

4 GEOLOGY OF THE LOTHIANS.

ments, the author begs leave to mention, that, though the phenomena may have been few which he considered worthy of minute description, this did not (if there was to be an attempt ata geological map of the Lothians) in any way lessen the labour. The country required to be tra- versed in all directions in search of appearances worthy of description, and if many excursions were made without the author finding any thing to describe, or even a rock of which a specimen was requisite, still there was the same ex- penditure of time and labour as would have taken place if these excursions had been fraught with interest.

As the Lothians have been traversed in all directions by geologists, little novelty is to be expected in the following pages; yet the author, by verifying and correcting from actual examination all previous accounts, and by adding his own observations, trusts that he will meet the wishes of the Wernerian Natural History Society. From accom- panying Professor Jameson in his excursions, he has derived much information, and has endeavoured to conduct his re- searches on the principles so ably taught by that experi- enced and celebrated geologist.

The speculative parts of the essay, and the views in re- gard to some points in the geology of the Lothians, bear on printed statements, and on others which, although not printed, are well known to the geologists of Edinburgh.

The maps accompanying this essay have been coloured, as far as possible, in accordance with Professor Jameson’s paper ‘ On the colouring of Geological Maps,” which is published in the first volume of the Wernerian Transac-

tions ; all the tints, however, have been made more intense,

INTRODUCTORY REMARKS. 5

as the dark engraving of the maps would, in many cases, have rendered the colours, if no deeper than those recom- mended in that paper, hardly visible.* The sections have been formed on the same system of colouring, and when other colours were required, those were selected which ap- peared to harmonize best. In regard to the objects of these sections it may be stated, that they were selected from all those points where the connections of the rocks are in any way interesting. The specimens which accom- pany the memoir, were selected in the same manner: no rock which the author considered interesting did he in- tentionally pass. In regard to the paucity of the speci- mens which have been collected in Linlithgowshire, it may be remarked, that few rocks were found which had not been already noticed in the counties of Haddington and Edin- burgh, and, as specimens of these had been selected, the fact of finding the same rocks in a different locality, ap- peared to render their collection unnecessary.

There still remains to be noticed one circumstance attend- ing this essay, and which may perhaps require explanation ; and this is the fact of there being in it no attempt to give details connected with the ‘* Coal Workings.” The reason which the author had for not entering on this part of the subject was, that he considered that such an investigation lay more in the way of the professional coal-viewer, than of one engaged in purely geological investigations. He did not, therefore, attempt to draw up sections or ground-plans of coal-workings, or to inquire into the quantities of known coal.

* The maps here referred to are those which were lodged with the es- say. They were those published by Mr Thomson of Edinburgh.

6 GEOLOGY OF THE LOTHIANS.

That his non-attenticn to this department, however, has in no way been the means of causing him to overlook ap- pearances of interest, in a scientific sense, he is inclined to believe, from the perfect similarity attending the rela- tions of those various beds of coal which have actually fallen

under his notice.

GENERAL DESCRIPTION. 7

THE LOTHIANS.

That portion of Scotland, which is bounded on the north by a line drawn from the Firth of Forth to the Firth of Clyde, is composed entirely of rocks of the Secondary and Transition classes. The former of these is traversed by ig- nigenous masses of the Felspar and Trap families, while the latter, besides being connected with these rocks, is broken through in several places by different granites and syenites. As it very generally happens that the oldest rocks of a country are those which attain the greatest altitude, while the newer formations which skirt them, form, according to their relative ages, either the hilly or the low land ; so here, the mountainous districts are composed of the older rocks, viz. the greywacke and transition slates (strata, which con- stitute the more or less uninterrupted high land which ex- tends from St Abb’s Head to Port Patrick in Wigtonshire), while the plains and less elevated country, exhibit only rocks referable to one of those groups which collectively form the great series of secondary formations.* All the strata of this class, which occur in the southern division of Scot- land, are to be referred to the carboniferous group. In several details these rocks will be found to differ from the

* The geognostical characters of the great high land mentioned in the text were first made known by Professor Jameson, who, indeed, was the first geologist who pointed out the occurrence of Transition rocks in Great Britain.

8 GEOLOGY OF THE LOTHIANS.

same as occurring in England; these differences are, however, only such as might be expected to be observ- able in a deposit extending over a large area: one part of a formation may be more fully developed in one sl- tuation than in another, or it may even be entirely awant- ing. In regard to the mutual associations of the Augitic and Felspathic masses, wemay remark that, although nonatu- ral sections exhibit the relative ages of these rocks ; still, from the examination of other districts, which are partially com- posed of both ; from the circumstance of the trap family be- ing so generally distributed among the carboniferous strata, and also from the eruptions of the trachytes (which may be considered as the modern analogues of the ancient porphy- ries and felspars), being, in general, anterior to those of rocks having a basaltic character, it is highly probable that the series of felspar masses, which is so generally associated with the Transition deposits, is of a formation more ancient than the basalts and greenstones. Inthe three counties the geo- gnostical structure of which it is the subject of this paper to describe, extensive districts of both Transition and Secondary strata occur, and, as we have just stated, the higher grounds are composed almost entirely of the older rocks. Before entering upon a minute topographical description of these two great‘classes, and also before we define their geogra- phical distribution, we shall describe both in a general man- ner ; and as in all geognostical descriptions, it appears to be most natural to follow the ascending series, so here we shall first notice the

TRANSITION ROCKS.

To classify, according to nature, the variousmineral masses which constitute the crust of our globe, has been the endea- vour of geologists, from that epoch in the history of the sci- ence when it was first discovered, that, to arrive at the know-

TRANSITION ROCKS. 9

ledge of the earth’s structure, wemust haverecourseto minute investigation, Many have proposed arrangements of the strata, which they, as the authors, have, of course, considered less liable to objection than those for which they were substi- tuting them. In all these arrangements, there has been no one division of the stratified part of the earth, more uni- versally considered false and unnatural, than that of the “ Transition class.” It has been said to have no natural ex- istence, but to be the mere creation of minds fettered by pre- conceived theories. As an objection to the term “transition”, some have urged that it is one derived from that theory, which affirms, that the rocks of this epoch were formed, du- ring the passage of the globe, from a state unfitted for the ex- istence of organic beings, to one which wascalculated for their preservation. If geologists have, in the course of their in- vestigations, come to any certainty concerning the ancient states of our globe, there is certainly no one doctrine sup- ported by a greater number of facts, than that of progres- sive development. Many remains have been adduced as belonging to beings, which held a place in the zoological scale, higher than was consistent with this theory. With one exception, however, all these remains have been found, on more accurate and better conducted examination, to be, instead of dissentient facts, beautiful proofs of its truth. The exception to which we refer* is as yet, perhaps, unexplained, and by some is considered as a stumbling block which must cause the fall of this theory. If, however, we remember that all the other exceptions have been explained, and that the * Crocodiles’ teeth” of Burdiehouse, which Lyell considered as indicative of the entire fallacy of this theory, have been found by Professor Jameson, and afterwards by Agassiz, to

“The occurrence of didelphic remains in the slate of Stonesfield, a member of the oolitic series.

10 GEOLOGY OF THE LOTHIANS.

belong tofishes; and that thesupposed 'T'rionyx of the old red sandstone of Caithness is also found to be a fish ; we may ex- pect that, on more extended investigations, the nature of the Stonesfield remains will appear in no way at variance with their geognostical position. As it seems most accordant with the rules of philosophical induction, to consider that as the best founded theory which is most generally applicable, so one solitary apparent exception should be the more dili- gently examined ; it ought to be viewed on every side and in all its details, whether it may be reconcilable with the theory against which it appears to militate, rather than be eagerly laid hold of, as a weapon to subvert one derived from apparently legitimate generalizations. To account for the non-appearance of highly organized remains in old rocks, it has been asserted that causes have existed adequate to effect their complete obliteration. ‘ Mechanical pressure, derangements by subterraneous movements, the action of chemical affinity,” have all been summoned up to account for the disappearance of animal remains which have (if wemay judge from evidence as strong as any attending a science, the facts of which are in few instances open to experiment), perhaps, never been in existence. How fickle in its actions must have been that “lapidifying process”! which could pre- serve, even toa delicate spine, a frail shell, and be too destruc- tive to alloweven the fragment of a bone of a bird or mammi- ferous animal to be visible in our older secondary rocks! It has been told us, that as the bottom of the existing ocean has not been dredged “throughout an area co-extensive with that occupied by the carboniferous rocks,” thus enabling us to calculate the chances which will bring up the relic of a mammifer ; so the fact of the non-appearance of these re- mains ought not to be considered as a proof of their non-ex-

TRANSITION ROCKS. Il

istence. But, as has been well remarked, ‘“‘ Every island, every continent, has formed part of an ancient bed of the ocean, and this ancient bed is exposed to the examination of thousands of observers in every degree of latitude not covered by polar snows.” Further, on finding this state- ment in a work which proposes a classification of tertiary strata, however ancient, by merely acquiring a knowledge of the extinct and existing species contained in each, are there not marks of inconsistency ? It is reckoned unsafe to judge of the utter absence of highly organized animals, in very old strata, by their not having as yet been found ; while the fact of a tertiary system of strata containing a greater per- centage of extinct shells than another, is considered as per- fectly demonstrative of its greater age. We are not wishing to inquire whether, in these instances, such a mode of exa- mination will infallibly lead to a just conclusion or not ; but it appears to be drawn as an inference from appearances pre- cisely similar to those, which have induced geologists to be- lieveinaprogression of development. As anargumentagainst the doctrine of progressive development, it has been affirmed that the corals and mollusca, which lived in the ancient seas, were not of a more simple structure than those which at pre- sent exist. Those, however, who advocated the opinion that, from the oldest fossiliferous deposit to the formations of our own epoch, there were proofs, from examining fossil bodies, that the standard of organization was gradually, and not instantaneously, raised, never, either directly or indirectly pronounced, as their opinion, that this ‘* progressive de- velopment” of organized beings was evinced by compar- ing the members of any one genus, as they occurred in con- secutive formations. It was never affirmed, as far as we are aware, by any geologist, that, if a certain natural class of organized fossil remains was observable in several forma-

12 GEOLOGY OF THE LOTHIANS.

tions, (the relative ages of which were indicated by superpo- sition) we must expect to find in the oldest of these forma- tions or series of strata, individuals of this natural class having a more simple structure than those imbedded in the newest. But it was insisted, and is yet (though some ima- gine that they see in the laws which now govern organized bodies in all their relations, and in the globe itself, an almost eternal and uniform system of legislation), that the earth’s strata exhibit proofs from their contents, that certain epochs have been characterized by the creation of the several main links of the zoological chain.

The term “ Transition” has been discarded by a celebrated geologist upon another ground ; but unfortunately the rea- son why the term was applied has been misunderstood. Mr Phillips, in his “ Guide to Geology,” after saying, that some geologists make a Transition class of rocks, affirms “ that this is needless, for such passages are not thought necessary to be marked in other instances.” When Werner named a certain class of rocks “ Transition,” it was done, not from discovering that they passed into the inferior or more crystal- line rocks, but from the conclusions which he drew from find- ing, that, in this series, for the first time, marks of animal and vegetable life occurred ; and that these were remains of beings which possessed a structure of the most simple na- ture. He so named this series of rocks, not because it pass- ed by mineral character, or alternation, into his ‘* Primitive class ;” but because his examination of its contents, and relations to asscciated rocks, made him draw the inference, that it had been formed during the passage of the globe, from a state in which vegetable and animal life existed not, to one fitted for its preservation.* ‘The term “ Transi-

* “They are supposed to have been deposited during the passage or

transition of the earth from its chaotic to its habitable state.”’-—Jameson’s Geognosy, p. 146. Edinburgh. 1808.

TRANSITION ROCKS. 13

tion” was theoretical ; but it is upheld by as many proofs as any other acquired portion of geological knowledge. As regards the objection to the term Transition, that it is un- natural, inasmuch as the rocks of this class pass into the infe- rior and more crystalline strata, and in the upper parts into those of secondary formation, it may be asked— Where is the series of rocks, which, however distinct and separate from its associated formations it may appear to be in one coun- try, has not been observed in other localities to alternate with and pass into them? If in all cases, however, these appearances were considered hostile to forming arrange- ments of the globe’s strata into great divisions, it is evi- dent that no classification could be formed from the rela- tive superposition of strata, and that one from some other system of phenomena would be necessary. Though these transitions of strata into each other, however, are conspi- cuous, there is still no reason why such transitions should be considered as affording a reason that from ‘“ gisement” strata should not be arranged. When viewed on the large scale, that on which all geological appearances ought to be viewed, the series which, from superposition, is to be acknowledged as of one formation, is also, from its being characterized by one or more classes of fossilized organic bodies, and in many instances by a wonderful similarity of mineral character, to be considered as the uninterrupted production of a certain geological epoch. The mineral characters of the transition rocks which occur in the Lothians, are limited. The Greywacke is, in general, a fine aggregate of minute grains of quartz and Lydian-stone, im- bedded in a base approaching to clay-slate, and containing scales of mica very generally distributed through it. In size, the components of the greywacke vary; they occur of all magnitudes, between that of the smallest sand and a fine

14 GEOLOGY OF THE LOTHIANS.

conglomerate ; and, when very compact, its mechanical na- ture is not very easily recognised. The Clay-slate, which is frequently associated with the greywacke, into which it passes, and with which it alternates, is of various shades of ash, bluish and smoke grey. Its general aspect is eart hy, and it never assumes that crystalline appearance which emi- nently characterizes that of an older formation, viz. the slate associated with gneiss and mica-slate. In the strata of grey- wacke there is also sometimes a striped appearance, identi- cal with that exhibited by the coal formation shales, and, m some districts, it contains numerous minute veins of mas- sive quartz, and layers of red hematite. The uniform sameness of the mineral characters of the Transition rocks, in countries far removed from each other, is a proof that the causes, from the actions of which they resulted, were almost universal; a fact which is at complete vari- ance with that system of geology, which sees only in the various rocks of our continents the long-continued action of existing causes. By the term “ universal,” however, it is not intended to be implied that at one period the earth was covered completely by an envelope of greywacke strata. Such an opinion, either in regard to it or any other forma- tion, is contradicted by every appearance. Butit is wished to be only understood as intimating that, during the epoch of the greywacke’s formation, it is probable that, when deposi- tions of strata took place over the globe, they were in cir- cumstances which allowed only the deposition of a grey- wacke. The idea which supposes, that, if a deposition of strata took place, that deposition must in all parts be simi- lar, because there existed a series of causes over the whole globe, which if called into action produced the same effects, is quite different from that’ which assumes that these causes acted at one given period over the whole globe. If all

TRANSITION ROCKS. 15

the deposits at present forming below the waters of the ocean, could be looked upon in one wide extended plain, it would be found that their mineral characters are so differ- ent in different places, that little similarity could be traced amongst them. That deposit which resulted from the ero- sion of a yranitic district, would present the characters of various red sandstones ; that which was produced by the comminution of quartz rock, would approach in character to a white sandstone ; while the formations which were formed from the disintegration of secondary or tertiary dis- tricts, would consist of various alternations of sands, gravels and clays. In all these supposed cases there is nothing si- milar to that uniformity of mineral character which is con- spicuous in older formations ; a fact which indicates that the causes effecting these formations were very general, and that similar circumstances existed over an immense portion, if not over all the globe at one period.

SECONDARY ROCKS.

Having now noticed generally the transition rocks of the Lothians, we shall next describe that series of Secondary strata which forms almost the whole of the counties of Edin- burgh, Haddington, and Linlithgow. The Secondary series of the Lothians is not composed of one and the same rock, but is, on the contrary, an example of a compound forma- tion, inasmuch as it is an assemblage of red and white sand- stones, variously coloured shales, and limestone, all of which are so associated with each other, that their synchronism of deposition is conspicuously evident. The white sandstone group of the Lothians has, as we have before stated, al- ways been considered as belonging to the Independent Coal Formation. This series differs in several respects from the coal-measures of England. It would certainly indicate 2

16 GEOLOGY OF THE LOTHIANS.

state of things entirely different from the present, if a for- mation, whose relative position in the crust of the globe was in one country correctly ascertained, exhibited in every other a strictly uniform sameness in its mineralogi- cal and fossilogical characters. If contemporaneous for- mations were identical in all their details, the determina- tion of strata would be conducted in a manner far different from what it is. Instead of traversing extensive districts, examining the relations of an unknown rock to others whose_ natures were apparent, and from superposition and other characters ascertaining geological equivalents, the mere view of a characteristic specimen would be sufficient ; and from geology being one of the most intellectual of Sciences, one which requires minute investigation, it would deserve hardly to be considered as an Art.

Authors, in describing that series of rocks which lies, in the regular succession, below the magnesian limestone, and above the transition formations, divide it into the Old Red Sand- stone, Mountain Limestone, and Coal Formation, drawing lines of demarcation between all these deposits. ‘Though, from observing, in some countries, that the position of one or all of these deposits is so unconformable, that it is only to be accounted for by the state of repose which existed during their several depositions, having been interrupted by disturbing causes, still there is no reason to conclude that this unconformability is to be observed in all countries. This is to assume, that igneous actions in the early ages of the world, differed entirely from those which now operate, and also that the upraisures of contemporaneous strata were themselves contemporaneous. A deposit which is completely separated from that which succeeds it in one country, may in another make a transition into it by numerous alterna- tions; and thus we have a proof that breaks in the sequence

SECONDARY ROCKS.—GENERAL RELATIONS. p ,

of strata, are, if viewed with the extent of the globe, only local. In the Lothians the divisions of old red sandstone, and mountain limestone, are unnatural ; for strata which, in one locality, might, from their relations to others, be considered as the old red sandstone, are, in another, found to occupy a position which renders this impossible. If these sandstones are found both above and below the mountain limestone, and are frequently seen to alternate with it on the large and small scale, it is evident that they form one deposit ; that the causes which produced them were not interrupted by paroxysms of violence. In the Lothians and in Fife, there are many points which evince that the old red sandstone, mountain limestone, and coal formation, can- not, as developed in these districts, naturally be separated.

Professor Jameson, in his Mineralogical Account of Dum- fries-shire, p. 165, enumerates several localities in the Lo- thians and in Germany, where red sandstone is found in- timately connected with the white sandstone series. In re- gard to the occurrence of red and brown sandstone, the Professor states, ‘‘ Ist, In lower Silesia, nearly the whole of the coal-field is composed of reddish-brown and cochineal coloured sandstone, with which great beds of coal alternate. Qdly, In the coal-field of Mid-Lothian we have the follow- ing instances of similar coloured sandstone occurring in the coal formation: a. In Dryden Water, near Loanhead, there are several beds of reddish-brown coloured sandstone, ac- companied by similar coloured ironstone in the coal for- mation. 6. Near Mr Cameron’s paper-mills, on the banks of the Esk, there are thick beds of reddish-coloured sand- stone, that evidently belong to the coal formation, and the same rock continues in the direction of the river, forming the picturesque cliffs of Hawthornden and Roslin, and ex- tendseven to Auchindinny Bridge. c. Immediately behind

themanse of Collinton there is a beautiful section of the vol. VII, B

18 GEOLOGY OF THE LOTHIANS .

coal-field. ‘The strata are semicircular and have their con- vexities uppermost, or form what is called a saddle; they are of a reddish-brown colour, and alternate with layers of greyish-black coloured slate-clay, and reddish-brown colour- ed clay-ironstone. On each extremity of the saddle rest the more common rocks, viz. grey-coloured sandstone, glo- bular clay-ironstone, &c. d. The rock on which Craigmillar Castle is situated, belongs to the coal formation of Mid-Lo- thian. It is composed of horizontal beds of greyish and red- dish-coloured sandstone, that alternate with their beds of reddish-coloured slate-clay and limestone conglomerate. _ e. The hill of Salisbury Crags belongs to the coal formation, and in it we observe repeated alternations of reddish-coloured sandstone, clay-ironstone, slate-clay, and limestone conglo- merate.”

In Fife, the coast between Dysart and Wemyss exhibits four alternations of the red with the white sandstone; and in the course of the Bevelaw Burn, a small stream which runs for a few miles at the base of the Pentland range, the white sandstone underlies the red. In other quarters this arrangement is completely reversed ; as on the coast of East Lothian, between the Cove and Dunglass Burn, where the white coal-sandstone overlies the red. By following the courses of the Dunglass, Bilsdean, and Thornton burns, the transitions of the white sandstone series into the red, are most satisfactorily displayed; the strata, as they recede from the sea, gradually assuming a red colour, till, at last, they pass into the red sandstone. In that part of the Esk river which runs past Arniston and Kirkhill, there are nu- merous alternations of the red with the white sandstone. Much also of the country intervening between Drummore- mill and Hawthornden, through which the Esk flows, is formed of the same red sandstone : its relations, however, to the white sandstone, are evident, and exhibit nothing fitted

SECONDARY ROCKS.—GENERAL RELATIONS. 19

to justify the misconceptions of some who have examined it.* The mountain limestone, which, if it preserved that position which it is generally found to occupy in other districts, would be a formation separating the white from the red sand- stone series, occurs in the Lothians connected with both. While making these statements indicating that the causes which produced the Secondary formations of the Lothians were uninterrupted during the deposition of the series, and that this circumstance accounts for the various alternations of its members, we may remark, that there has been a source of error in the belief, that in all instances three distinct de- posits,+ viz., the Old Red Sandstone, the Mountain Lime-

* Dr Hibbert, in his paper “ On the Limestone of Burdiehouse,” publish- ed in the Transactions of the Royal Society of Edinburgh, vol. xiii., page 137, affirms, that, by ignigenous action, “there has been an emer- gence of beds even inferior to the carboniferous group,” and cites the Pentlands and the coast of North Berwick as localities. The strata ex- posed there, however, are all of the same general nature as the red sand- stones of other places, which, by their relations to the white sandstones, so clearly indicate that hoth series constitute one contemporaneous formation. The red sandstone of HawTHoRNDEN, exhibited also to Dr H. some appearances which caused this observer to believe that it had been deposited soon after the formation of the Transition rocks. In re- gard to what these were we are ignorant ; but if viewed in allits relations, it will be found to form only one of those deposits of red sandstone, which, with those of white sandstone, coal, and shale, form the second- ary system of the Lothians, and geognostically represent the coal forma- tion.

+ As an instance of this we may mention the conclusions to which Messrs Sedgwick and Murchison came, after examining the secondary formations of the island of Arran. In that island two red sandstones oc- cur, the one above, the other below, the strata of white sandstone con- taining beds of coal, while the Mountain Limestone occurs interstratified with both. After examining this district, these geologists were led to consider that series of red sandstone strata, which was in the more im- mediate vicinity of the old rocks, as the Scottish representative of the old red sandstone of England : the assemblage of white sandstone was by them described as the Coal formation ; while the red sandstone which lay above it, was stated to be the equivalent of the new red sandstone of England, differing from it, however, in this circumstance, that in Arran it was conformable with the coal formation. By

B2

20 GEOLOGY OF THE LOTHIANS.

stone, and the Coal Formation, separate, without ever blending into each other, the New Red Sandstone from the Transition Rocks. It is this alone which has made some declare that the series of red sandstone strata, which, in some places, is found above the true Coal Deposits, be- longs to the New Red Sandstone. 'To determine the age of strata, they must be examined through their whole extent, and their position in the globe’s crust is only to be ascertain- ed by studying all their various phenomena, Though the red sandstone, white sandstone, and limestone, of the Lothians, may not, from the circumstance of their being so intimately connected, be considered exactly similar to the carboniferous series of other districts, though, perhaps, they exhibit not that invariableness of position which characterizes them elsewhere, still, in the circumstance of the red sandstone and conglomerate being most remarkably developed in those parts of the country which are in the vicinity of the older rocks, they exhibit an appearance similar to that observable in other and more distant localities. The conglomerates of the lower parts of the series are, from the size of the mass- es which compose them, highly indicative of the great me- chanical action which must have operated in their forma- tion.

Though conchological contents characteristic of a forma- tion, the position of which relatively to others is known, be found in districts at a great distance from those in which the

By comparing this series of red and white sandstone with the same as developed in the Lothians, or even in the adjoining coast of Ayrshire, the identity of the two is easily made out, and that sandstone which was by these gentlemen considered as the new red sandstone, becomes on- ly a member of the great secondary series of the Lothians, no one of which can be naturally separated from the others, if throughout the whole extent of their distribution we examine their mode of arrangement relatively to each other. This view of the sandstone of Arran was pro- posed by Professor Jameson, in one of a series of memoirs on the geo- logy of Arran, read to the Wernerian Society several years ago.

SECONDARY ROCKS.—GENERAL RELATIONS. 21

deposit of an understood geological age occurs, still we are not to consider that these far separated deposits must neces- sarily be of the same age. That they may be, is possible, but it is as probable that they may not, and their evidence is never to be opposed to that affordedby superposition. That the red conglomerates and sandstones of the Lo- thians are not derived from the consolidation of sands and rolled masses brought from a great distance, is apparent, from the fact that no rock-fragments are found in them, but such as occur in situ in their more immediate neigh- bourhood. That vast deposit of red sandstone conglo- merate which skirts continuously the Greywacke formation of the Lammermuirs, from Redheugh in Berwickshire to Heartside in Haddingtonshire, and which rises into moun- tain masses in several parts, is entirely composed of variously shaped rolled masses of greywacke and transition-slate. Be- sides containing masses of the stratified or Neptunian rocks, on which the conglomerates rest, they also, though rarely, include rolled masses of members of the felspar series. In the red sandstone hill of Chesters, near the village of Spott in East Lothian, masses of felspar-porphyry occur, and, in the conglomerates of Carlops and Hab- bie’s How, fragments of compact felspar are abundant. These appearances therefore indicate that all the mem- bers of the felspar series of the Lothians are not newer than the carboniferous formations ; but prove, on the con- trary, that by being subjected to aqueous attrition, they have contributed to the formation of these strata. The white sandstone series, which alternates with the red, and has been entitled The Independent Coal Formation, is, like the red sandstone, compound ; it is an assemblage of white sandstones, slate-clay, bituminous shale, clay ironstone, and coal, In the Red Sandstone series, the sandstone is in ge-

29 GEOLOGY OF THE LOTHIANS.

neral of a bright red colour, and conglomerates are abun- dant; but, as the name implies, those of the white sand- _stone group are generally white, and conglomerates are com- paratively rare. The shales accompanying the red sand- stone strata, are of various shades of blue, green, yellow, and red; while those associated with the white sandstone are generally grey : bituminous shale also is very rare in the former series, while in the latter it is largely deve- loped. The abundant diffusion of coal beds in the white sandstone series, is another characteristic feature of this group, for when these do occur connected with red sand- stone, they are, with few exceptions, situated in what may be considered as a debateable ground between the two classes of strata, and in those portions which partake of characters of both. Another rock which we have men- tioned as occurring in the Lothians, is the Mountain Lime- stone. This, as we have previously stated, is not here, as in those districts of England or Ireland where it occurs a distinct and separate formation. It occurs in the red sandstone series of the Lothians, forming, in some loca- lities, considerable beds, but its comparative scarcity in it is to be considered as a mark eminently distinguishing this series from that of the white sandstone group.

Having now described the general relations of the various secondary rocks of the Lothians to each other, we shall enumerate their several mineralogical ranges of character. The red sandstone, which we have mentioned as the fre- quent occupant of the lowest part of the series, is in general a fine aggregate of grains of quartz and felspar, held together by a basis of ferruginous clay; scales of mica are profusely distributed through it, and frequently, by their great abundance, it assumes a slaty structure. A coarse conglomerate forms a part of the red sandstone se-

SECONDARY ROCKS.—MINERALOGICAL CHARACTERS, 23

ries. It is of two kinds; one variety, as we have before stated, being entirely formed of variously sized masses of grey wacke and its slates, and occurring in immediate connec- tion with the transition ranges of the Lammermuirs ; while another, which is met with only in different parts of the Pentland district, and in the neighbourhood of Penny- cuick, is composed of rounded masses of quartz-rock, grey- wacke, flinty-slate, felspar, and common jasper, imbedded in a base of similar fragments. At Danskin, in East Lo- thian, and in the mountain valley of Glencorse, both con- glomerates are well marked. The hills which occur on both sides of Dunglass Burn, are composed of this rock, which has resulted from the disintegration of the grey- wacke, and the masses which form it are on such a co- lossal scale, and held together so very loosely, that it might be mistaken for a formation of very modern date. The red sandstone forms extensive districts in Berwickshire, and much of that part of East Lothian which ranges along the northern front of the Lammermuirs. As that of several other parts of Scotland, the red sandstone of the Lothians is eminently characterized by containing in many places nu- merous circular yellowish-green markings, in the centre of which there is frequently a black coloured spot. Though red is the predominating colour of the red sandstone series, still, associated with it, there are other sandstones of various shades of brown and grey. Variegated sandstones are abundant, brown or red markings occurring in a field of white sand- stone ; as examples of these,