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THE GEOLOGY OF RATHVEN AND ENZIE. 331

VIII.—The Geology of Rathven and Enzie, Banffshire. By THOMAS D. WALLACE, F.E.S.A. Scot., Head Master Inverness High School.

(Read 20th May 1880.) • The district about to be described lies along the south shore of the Moray Firth for 9 miles, and extends for a distance of 2 or 3 miles from the shore southwards. It is bounded on the north by the Moray Firth, on the east by the Cullen Burn, on the south by a low range of hills, of no considerable height, and on the west by the Eiver Spey. The greater portion of the soil belongs to the Duke of Eich- mond and Gordon on the west, and Lord Seafield on the east, with several smaller proprietors intervening. The district comprises the parishes of Eathven and Enzie, and lies almost entirely in Banffshire. The coast throughout its greater length is bold and rocky, rising perpendicularly from 87 feet on the west to 176 feet on the east. The surface rises gradually from the top of this cliff to the heights which bound the district on the south, and which are known by different names, and terminating in the east with the well-known " Bin " of Cullen, 1050 feet above sea-level. The general appearance of the surface is undulating or hummocky, and may be conveniently divided into two portions by the turnpike road from Fochabers to Banff. The highest parts on the north side of the road are a small patch of wood known by the name of the " Slack," just behind the Enzie post-office, and which rises to 198 feet above sea- level, and the " Bauds of Cullen," which stands 270 feet. On the north side of the road the land rises by a series of hummocks, and in some places by well-marked terraces, to 729 feet at the west, and 1050 feet on the east side. The district is for the most part highly cultivated and well wooded. Some of the soil is thin and sandy, while considerable portions are still covered with native broom and heather. It is diversified by hillocks of sand, gravel, and clay, separated by large tracts of marshy land, now drained. From the farm of Wester Bogs, in the parish of Enzie, sand was at one time shipped for moulding purposes, for which it was considered admirably suitable. It is drained by five considerable streams, all of which enter the sea, after making deep cuttings through the different rock formations. These cuttings exhibit sections, which present a Downloaded from http://trned.lyellcollection.org/ at Nanyang Technological University on June 17, 2015

332 EDINBURGH GEOLOGICAL SOCIETY. variety of features of the highest instructive value to the earnest student of nature. They would call forth the admiration of the master geologist, and fill with awe and astonishment the novice in science. The district has long justly maintained a high reputation for its Old Red Sandstone fossil fish remains, which are very beautifully preserved in the burn of Tynet, about 4 miles east of Fochabers. As the sections displayed in each of these burns have separate features and special points of interest, it will be best to describe each individually, and afterwards to correlate them. Tynet Burn. To begin with Tynet Burn, which lies to the west, we shall describe the formation from the sea upwards. It enters the sea a little to the west of Port Gordon, through an enormous bank of pebbles which has been thrown up by the tide. No better example could be found of the' rounding and smooth­ ing power of the sea upon hard pieces of rock, than in this bank. They are dashed to and fro, up and down, by each succeeding wave, with great violence, and in stormy weather with a noise quite deafening, and which can be heard miles distant. This bank extends from a little to the west of Port Gordon towards the mouth of the Spey. On it may be picked up pieces of lias, so well developed at Ethie, on the north shore of the firth, and containing the same fossils as are seen so abundantly in the rock in situ. This shows a tendency of the tide to carry from the north to the south side of the firth. This same tendency is a feature peculiar to the whole firth. Several parallel ridges of pebbles may be seen in many places, and sometimes so straight that it has been remarked that the hollows between them would make capital rifle-ranges. These ridges are caused by the sea throwing up sometimes more and sometimes less pebbles on the shore. In a storm the pebbles are thrown up into a high bank. In ordinary weather a new ridge is commenced on the side of the high one, and near its base. The latter is added to until a new ridge is formed, with a hollow between the two summits. For the distance of a mile from its mouth the burn flows through a deposit of gravel, clay, and sand. The first appearance of rock is at Windsoer, where it consists of a dark red schistose sandstone, interbedded with calcareous shale containing nodules, in which, as yet, no fish remains have been found, and which are highly crystalline. Similar rock is found all along the banks of the burn, until the Lower Tynet Mill is reached, within a few hundred yards of which a coarse gritty rock appears to dip under the beds at Windsoer, in the usual manner, at an angle of 10° or 15° to the north. A few yards up from this bed a coarse pebbly conglomerate Downloaded from http://trned.lyellcollection.org/ at Nanyang Technological University on June 17, 2015

THE GEOLOGY OF RATHVEN AND ENZIE. 333 is seen to fill up curious interstices among the other beds, but not interbedded with them. This conglomerate differs slightly from the fundamental Old Eed conglomerate in the neighbour­ hood of Inverness. The difference is chiefly in composition. While the pebbles are rounded in the usual way, the matrix in which they are imbedded is quite friable, so much so, that with a single blow of the hammer large masses can be easily detached. This may be taken as a pretty general characteristic of the con­ glomerate of the district. The masses which are seen to lie among the shales and sand­ stones at Tynet suggest to the mind a quantity of rubbish tilted over the end of a bank into an irregular cavity. Although the conglomerate fills up a space between the sand­ stones, yet these are not disturbed in their dip; nor could I find anything to convince me that these had been brought into contact by a true fault. The whole of the Old Eed Sandstone series in the district consist of sandstones and shales, interbedded with conglomerates. The famous fish beds are behind the Lower Mill of Tynet, There are in all three beds. In the lowest have been found Ooccosteus. In the next, at a height of about 40 feet up the cliff, have been found Osteolepis, Pterichthis, &c In the highest, which is about 4£ feet from the last, Diplopteris, Cheirolepis, Cheiracanthus, &c, are numerous. The fossils are found in thin, flat calcareous nodules, imbedded in thin bands of light grey shale. This is the finest of all the fossil beds in the north, but is also the most difficult to work. Quite close to the conglomerate, fossil fish have been obtained. A thick deposit of gritty conglomerate is seen at a short distance from the mill door. Specimens of Ooccosteus have been dug from under this bed by several local and other workers. Several good collections from these beds may be seen in the possession of gentlemen in the district. Among these may be mentioned that belonging to His Grace the Duke of Eichmond and Gordon; the Eev. James Kyle, Preshome; Mr Simpson, merchant, Holl; Mr Thomson, farmer, Gollachy; and the author of this paper, in the Inverness High School. The schists on which the Old Eed rests are seen to great advantage in the burns of Tarrymout and Armachy, which join and form the Tynet Burn. The contortions, foldings, and false beddings of these schists in some places are really wonderful, and almost baffle description. Gollachy Bum. The Old Eed sandstones, shales, and conglomerates next appear to the east in Gollachy Burn, which presents a very interesting feature in northern geology. Within tide-mark, at Downloaded from http://trned.lyellcollection.org/ at Nanyang Technological University on June 17, 2015

334 EDINBURGH GEOLOGICAL SOCIETY. the mouth of this burn, the rock crops out and consists of a dark red conglomerate, interbedded rudely with a compact sandstone of the same colour, and showing ripple-markings. The conglomerate consists of pebbles of ferruginous quartz, quartzites, sandstone, and schist imbedded in a friable matrix, and dips at an angle of 5° N. About 50 yards from this point, at a bend in the stream, fine sections of sandstone and conglomerate are exposed to view. The first is about 20 yards long, and shows the dip to be from 5° to 7° N. The second shows both dip and strike for 31 yards. This is perhaps the best section of conglomerate in the district. The pebbles are similar to those in the rock on the shore, with an occasional porphyry and fragments of Diabase, to be mentioned afterwards. The latter is easily decomposed by the action of the air and moisture, many of them being reduced to a soft pulpy mass. The conglomerates here, as in other parts of the same district, are very friable, which renders the pebbles easily detached, and also the whole mass to suffer very much from sub-aerial denudation. Underlying the sandstones is a bed of coarse limestone which dips at one out-crop at the very high angle of 36° or 40° in the same northerly direction as the overlying beds. One bed of sandstone in the immediate proximity to the limestone dips at an angle of from 15° to 17° N.W. This change of dip naturally suggest an inquiry into the cause. This is not far to seek; for a few yards farther up, the Old Mill of Gollachy stands on a rock which seems to have no lithological affinity to the surrounding strata. The mill is built upon hard compact masses of this rock, which at a little distance presents a slightly columnar appearance. I visited this spot at Christmas 1877, and carried away speci­ mens of the rock under the mill, believing that I had found a volcanic ash. Although not volcanic ash, it has since been proved to be a true volcanic rock. It is thus referred to by Mr Archibald Geikie, LL.D., F.E.S., iri his paper on the "Old Eed Sandstones of Western Europe":— " Mr J. G. Wilson, who has been entrusted with the mapping of the district (Buckie) above referred to, has made the interesting discovery of a bed of Diabase-porphyrite interstratified in the lower part of the section of sandstone and conglomerate in Gollachy Burn, near Buckie. This is a true lava flow. He has observed pebbles of this rock in some of the overlying strata. "With the exception of the Ehynie Diabase near Huntly, already referred to, it is the only example yet noticed of the occurrence of contemporaneous volcanic rocks in the Lower Old Eed Sandstone on the north side of the Grampian Mountains until we reach the far distant Shetlands, I have examined it Downloaded from http://trned.lyellcollection.org/ at Nanyang Technological University on June 17, 2015

THE GEOLOGY OF RATHVEN AND ENZIE. 335 microscopically, and find it to be identical in character with some lavas of the Old Eed Sandstones of central Scotland. It has a characteristic porphyry ground-mass, through which are scattered decayed plagioclase crystals, and numerous opaque ferruginous pseudomorphs, many of which appear to represent former augite." Close to this mass of Diabase, and on the opposite side of the stream, the rock which overlies the compact Diabase, and seems to be a modified form of it, is crushed and broken up into small rectangular pieces. Close to this the stream flows over the same rock, which shows a transverse section of the vertical mass on the opposite bank, and exhibits the same crushed and broken appearance.* The strata surrounding the lava-flow, as far as can be made out from the sections exposed, may be described as follows:— 1. Close to the compact Diabase, at the Old Mill, and on the opposite side of the stream, the rock which overlies the compact mass is broken up into small rectangular pieces. Close to this the stream flows over the same rock, which shows a horizontal section, crushed and broken in the same manner. 2. Between the sea and the Old Mill the dip is altered, while above the Mill no such alteration could be detected. 3. Fragments of Diabase are found in the overlying beds of conglomerate and breccia, which in some places seem to consist almost entirely of it. Where the conglomerate is subjected to constant moisture, it assumes the appearance of a mass of decomposed Diabase. The conglomerate in one place shows a very distinct slip; one pebble being cut so as to show the distance of displacement. 4. A little above the Mill of Gollachy, and about a quarter of a mile above the Old Mill, Mr Thomson, farmer, Gollachy, con­ ducted me in July 1879 to a bed of Old Eed Sandstone, in which he had detected traces of fossil fish. After some digging, we were rewarded with very characteristic fragments of Coccosteus. This fossiliferous bed, which is about 18 inches thick, lies between two deposits of Breccia, consisting almost entirely of angular fragments of Diabase. The rock in which the fossils are found is highly altered, and as far as the frag­ mentary fossil evidence goes, seems to be the Tynet Coccosteus bed metamorphosed. Having established the fact of the existence of a true fos­ siliferous deposit here, I revisited the spot, and found the same bed continued farther up the stream, with the same overlying deposits. A very interesting block, the surface of which was covered with scales of Coccosteus, lay in the bed of the stream.

* The wall of the mill stands upon this compact mass, which rests on the transverse section of the broken rock, and it seems difficult to explain why the same compact mass is not seen at the same level on the opposite bank. Downloaded from http://trned.lyellcollection.org/ at Nanyang Technological University on June 17, 2015

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It consisted of granular quartzite, containing concretions of a red flinty mass. I revisited this spot, Christmas 1879, and broke up this boulder, and found a fine fragment of Coccosteus. The rock was not in situ, but from its contents it would appear to have formed a part of the Coccosteus bed, which had been much altered and detached from the bed, which no doubt had cropped out further up the stream, and carried down to where it had been found, by the action of the water. The last out­ crop of this fossiliferous bed is opposite the farm of Auchentae, where it is seen distinctly to lie between two strata of Breccia. From the above observations, extending over a number of years, I am inclined to conclude that the lava had burst through the underlying deposits, somewhere near this locality, and over­ flowed the previously deposited strata containing Old Eed Sandstone fossils. The limestone already referred to was once burned for agri­ cultural and building purposes. Eemains of an old kiln may still be seen near the mouth of the Gollachy Burn. A thin vein of Barytes or heavy spar runs through the broken rock which overlies the Diabase. Limestone obtained from under high-water-mark was burned in 1843 between this burn and the village of Buckie. Beautiful crystals of calc-spar were dug out of the strata underlying and almost under the compact Diabase rock at the Old Mill

Buckie Burn. Passing along the shore from Gollachy, the Old Eed Sandstone can be traced as far as the mouth of the Buckie Burn. In some places along the shore good ripple-markings are to be seen, and in one place indications of fossils. The schists appear on the shore at the mouth of the Buckie Burn, and can be traced up as far as the Eoman Catholic Chapel, where there is a good development of Old Eed Breccia. A few yards further up there are three junctions of the two systems. The first of these shows the Breccia dipping to the N. 7° or 8°, and lying unconformably upon the schists, which dip to the S. at an angle of 50°. The thickness of the Breccia as seen above the schists here is 20 or 25 feet. The section exposes about 25 yards of the rock. The Breccia contains much iron, and is largely made up of fragments of the underlying schists. Further up the burn, at the Old Mill of Buckie, there is another section which exposes the rock for about 35 yards, and shows the Old Eed lying unconformably upon the schists. From this up to the Mains of Buckie, the stream flows over a fine development of these schists. Downloaded from http://trned.lyellcollection.org/ at Nanyang Technological University on June 17, 2015

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Cullen. We will now pass on towards the east (to Cullen), where the Old Eed Sandstone again appears in the beautiful little bay of Cullen. Our description will read from Cullen westwards. The first objects of interest are the celebrated " Three Kings of Cullen," which are large masses of whitish quartzite, which have appa­ rently bid defiance to wind and tide, when the surrounding strata have been swept away. They are evidently the remains of what was once a continuous vein of quartzite running through the schists. Similar veins of quartzite are quite common in the schists on the same shore. One very characteristic one at the Old Castle of Findlater shows splendid ripple-markings. A little to the west, and standing out boldly in relief, are two large masses of conglomerate (Old Eed), which show inter- beddings of fine sandstone. It is about 60 feet high, and measures 33 yards in its greatest length. A little further to the west the schists appear, and form the picturesque cliffs between Cullen and Buckie. One or two points are worthy of special notice. One is to the east of Portnockie, where the sandstone lies unconformably upon the schists, which dip 55° S. on the north side of the bay. The schists here, as in other parts of the coast, have been cut through by the sea, or worn into caves, into some of which the tide still rises, while others are far from high- water-mark. The cliff here is 100 feet high, and the conglo­ merate which overlies the schists is about 25 feet thick. Here may be seen a fine example of sub-aerial denudation. A path at one time had been used along the edge of the cliff where the Old Eed Sandstone and the schists join, but is now abandoned on account of the greater portion of it being quite denuded away by the action of the weather. The attention of the geologist is next attracted by the " Bow Eock," which is a fine example of marine denudation. It is an outlier, through which the sea has cut a passage in the form of a "bow." The height of the "bow" is about 50 or 60 feet, and the width 30 feet. All along the shore the caves and passages in the rocks are the favourite haunts of the rock pigeon, cormorant, and other sea fowl The neighbourhood of Portnockie presents the finest develop­ ment of the schists in this part of the shore now under con­ sideration. Here the action of the sea can be seen to perfection. The waters tumble in and out the caves, and through the passages in the rocks, in such a manner that in a storm the scene must be positively grand in the extreme. Downloaded from http://trned.lyellcollection.org/ at Nanyang Technological University on June 17, 2015

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Some of the caves have been so acted upon that the roofs have fallen in, a feature which can be also seen in the caves in the sandstone to the west of Lossiemouth. In some places the sea has tunnelled through the softer parts of the schists, leaving intricate passages. In others, large masses of rock have become entirely isolated, and stand as magnificent outliers, at different distances from the shore. At Portnockie, the Old Eed Sandstone appears lying upon the schists. The village is evidently built upon the remains of the Old Eed deposit, which at one time covered the schists which are now so well developed all along the shore.

Schists. These Banffshire schists are older than the Old Eed Sand­ stone formations, and, as far as the evidence at present goes, they are newer than the Gneiss, with which we are so familiar in many parts of the Highlands. In the valley of the Spey, micaceous gneissose rocks pass underneath the quartzites of Ben Aigan, while these quartzites dip conformably beneath the Banffshire schists at Boharm. So that from the Spey to Boharm there would seem to be an ascending series of gneiss, quartzites, schists, and Old Eed Sandstone. These Banffshire schists are in every way more interesting than the ordinary gneiss of the Highlands. They are more numerous and varied in their character and contents. There are clayslates, mica schists, andalusite, chiastolite, and cyanite schists, associated with quartzites, serpentines, limestones, diorites, &c. From their contents, some mineralogists have endeavoured to assign to them their exact position in the geological scale. The following is the series of crystalline rocks in North America:— 6. Upper Taconian. 5. Lower Taconian. 4 Montalban. 3. Huronian. 2. Norian.

x 1. Laurentian. These different series were considered by the advocates of the metamorphic theory to be altered pre-existant rocks. Sterry Hunt regards them " as many great stratified series, which before the Cambrian time existed in their present crystalline condition, and had been successively subjected to the accidents of uplift, contortion, and denudation, so that the newer Eozoic groups were, at the beginning of the Paleozoic period, distributed irregularly over the floor of fundamental Laurentian gneiss." Downloaded from http://trned.lyellcollection.org/ at Nanyang Technological University on June 17, 2015

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Sterry Hunt believes that there is a similarity between the crystalline rocks of North America and those of the British Isles. Among the crystalline rocks of Donegal he has indicated representatives of Laurentian, Montalban, and Huronian; and the latter, he has recently observed, largely developed in Argyleshire and Perthshire. To the Huronian he also refers the green schists of Anglesea and Carnarvon, in both of which regions the Orthofelsite or Halleflinta series at the base of the Huronian (the so-called porphyries), and likewise the more ancient gneisses, are well represented. Professor Heddle says:—" Should the conjecture of Murchison and Geikie, that the gneiss of the west coast is of Laurentian age, prove to be correct (as, indeed, there can be little doubt), and should the Shetland rocks, with equal correctness, be assigned to the Huronian, then in the philite schists of Boharm and Clova, the andalusite schists of Coreen, the staurolitic and andalusite schists of Kinnairdy, the quartzites and limestones of the Vale of Deskford, Ben Cullen, and away to the south, the serpentines, granular hornblendic rocks, chiastolite and margaroditic schists of Portsoy, we have another series equally accordant with the Taconian of America." In none of the geological formations in the neighbourhood of Inverness are these Banffshire schists represented. The only thing resembling them is the rock underlying the Old Eed Sandstone of Dunchea, which was pointed out in my paper on the " Structural Geology of Strathnairn," as differing from the ordinary Gneiss in appearance. In the absence, however, of a minute mineralogical examina­ tion of the latter, it would be unwise to assert that the under­ lying rock on Dunchea was a fragment of the eastern schists.

Travelled Boulders. Having revisited this district at Christmas 1879, and ex­ amined it more carefully than on former occasions, I found further proof of the eastern flow of the great ice sheet that at one time covered or traversed the whole of the south shore of the Moray Firth.' In the neighbourhood of the Enzie post-office I found numerous boulders of the so-called Ben Wyves granite. None of them were so large as the one which was dug out during the excavations for the Buckie harbour, and seen on a former occasion. Numerous small boulders of the Elgin Cornstones lie scattered all over the lower part of the district. Several are to be seen in the Gollachy Burn, a little to the west of Buckie. Downloaded from http://trned.lyellcollection.org/ at Nanyang Technological University on June 17, 2015

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Conglomerate boulders are rather rare. Except the few remaining stones forming the "Stone Circle of Dryburn," I found only one, about a quarter of a mile east from Dryburn. A very characteristic specimen of Kinsteary granite (near Nairn) was dug out during the excavations for the new harbour at Buckie. Smaller pieces may easily be picked up on the fields and along the shore. A well marked feature of the schists which underlie the Old Eed in this district, is the frequent occurrence of large veins of calk spar, quartz, and quartzite. Specimens -of these are also numerous in the drift. A fine specimen of cairngorm, which was water-worn, was picked up by a labourer on the high ground, locally known as the " Hill of Altmore," to the south of the district. It measures 2 inches thick at the one end and 3 at the other. It is about 4| inches in breadth. This man, ignorant of its value, took it to Aberdeen, and had it polished on both sides by some friend at the granite works. This has rendered it quite transparent, so that one can read with the greatest ease any book placed under it. As far as the boulder evidence goes, it proves conclusively, I think, that the ice-flow was from the west, or a little to the south of west. One section of boulder clay is deserving of notice. It is in the wood of Pathhead, on the estate of Cairnfield, and a little to the south of the Enzie post-office. It consists of a fine plastic clay, of a dark bluish-black colour, overlaid by the well-known red boulder clay. The blue clay would point to the denudation of the schists, and the red to that of the Old Eed Sandstone. Notwithstanding a very minute examination of every burn in the district, I failed to find any of the blue clay on the lower ground. This I take to be an additional proof of the easterly flow of the ice. All along the south shore of the Moray Firth, lie scattered boulders of sandstones and Conglomerates, Dirriemore, and other granites, and the sandstones and cornstones of Elgin. In the neighbourhood of Inverness these would indicate a drift from the N.N.W., and tending E. or a little to the N. of E. Boulders of hornblende, which can also be picked up, might come from the N.W. The only places where I have seen horn­ blende in situ, in the neighbourhood of Inverness, are at Eaven's Eock, near Strathpeffer, and on the north shore of Loch Ness.