Report on the Geology of the County of Londonderry and of Parts of Tyrone and Fermanagh

www.e-rara.ch Report on the geology of the county of Londonderry and of parts of Tyrone and Fermanagh Portlock, Joseph Ellison Dublin, 1843 ETH-Bibliothek Zürich Shelf Mark: Rar 30883 Persistent Link: http://dx.doi.org/10.3931/e-rara-72691 Chapter II. www.e-rara.ch Die Plattform e-rara.ch macht die in Schweizer Bibliotheken vorhandenen Drucke online verfügbar. Das Spektrum reicht von Büchern über Karten bis zu illustrierten Materialien – von den Anfängen des Buchdrucks bis ins 20. Jahrhundert. e-rara.ch provides online access to rare books available in Swiss libraries. The holdings extend from books and maps to illustrated material – from the beginnings of printing to the 20th century. e-rara.ch met en ligne des reproductions numériques d’imprimés conservés dans les bibliothèques de Suisse. L’éventail va des livres aux documents iconographiques en passant par les cartes – des débuts de l’imprimerie jusqu’au 20e siècle. e-rara.ch mette a disposizione in rete le edizioni antiche conservate nelle biblioteche svizzere. La collezione comprende libri, carte geografiche e materiale illustrato che risalgono agli inizi della tipografia fino ad arrivare al XX secolo. Nutzungsbedingungen Dieses Digitalisat kann kostenfrei heruntergeladen werden. Die Lizenzierungsart und die Nutzungsbedingungen sind individuell zu jedem Dokument in den Titelinformationen angegeben. Für weitere Informationen siehe auch [Link] Terms of Use This digital copy can be downloaded free of charge. The type of licensing and the terms of use are indicated in the title information for each document individually. For further information please refer to the terms of use on [Link] Conditions d'utilisation Ce document numérique peut être téléchargé gratuitement. Son statut juridique et ses conditions d'utilisation sont précisés dans sa notice détaillée. Pour de plus amples informations, voir [Link] Condizioni di utilizzo Questo documento può essere scaricato gratuitamente. Il tipo di licenza e le condizioni di utilizzo sono indicate nella notizia bibliografica del singolo documento. Per ulteriori informazioni vedi anche [Link] 22 HE VIEW OF THE VVOKKS CHAPTER II. * REVIEW OF THE WORKS OF PRECEDING WRITERS. Little of an early date , has been recorded on the geology of this country . Passing by for the present , notices on the Giant ’s Causeway, which appeared in the early volumes of the Philo¬ sophical Transactions , one of the first papers which can be incidentally referred to geology is a communication made to the Royal Society by the Archbishop * of Dublin , in the year 1708. This paper explains the manner of manuring lands, by sea shells, as practised in the counties of Londonderry and Donegal. “ Marl is not used that I have observed in the north , but about the sea-side the great manure is shells : any one that will look into the map, will see how the bay of London , com¬ monly called Lough -Foyle , lies. Towards the eastern part of it, there lie several eminences that hardly appear at low- water ; these are made of shells of sea-fish of all sorts, more particularly of perriwinkle , cockles, limpet, &c. The country¬ men come with boats at low-water , and carry loads of these shells awayan application of the shell banks or islands, which has been continued to the present day. The Archbishop proceeds, “ almost about the bay of Lon¬ donderry , if you dig a foot or two it yields shells, and whole hanks are made up of them ; but these, though more entire than such as are brought out of the shell island, are not so profitable for manure .” I observed in a place near Newtown -Lama- vady , about two miles from the sea, a bed of shells such as lie on the strand ; the place was covered with a scurf of wet spongy earth about a foot thick ; the country people used the shells, but they were not reckoned so good as those that are found in the sea or near it .” Here , then , is a distinct notice of one of the tertiary deposits which will hereafter be described ; but whether it was identical in position with any of those which can yet be studied, or was in course of time entirely worked out and * William King, Bishop of Derry 1691 ; Archbishop of Dublin 1702, OF PRECEDING WRITERS. 23 obliterated , cannot now be determined ; it may however be con¬ jectured , that as the shells in the newer pliocene deposits of this country are not sufficiently abundant to be profitably used as manure, though the calcareous clay in which they are imbedded might occasionally be so applied with advantage , the shells mentioned by the Archbishop, were probably related to more recent shelly deposits such as that of Portrush, first noticed by Mr . Smith of Jordan Hill . Another passage in this paper , though foreign to the present subject, deserves to be quoted, “ the inconveniences of burning the turf are first, that such burning defiles the air and causeth rain and wind the Archbishop anticipating Mr . Espy in one of the practical illustrations of his Theory of Storms. 1725.—In the Anthologia Hibernica , for January , 1794, the design of Dr . Nicolson, Bishop of Derry , to write the Natural History of his diocese, is referred to by a writer , under the sig¬ nature D . By his statement it appears that the Bishop requested his clergy to make collections in their respective parishes, and that many complied, particularly the Rev . Robert Innes, Rector of Magilligan , who published in London , A.D . 1732, seven letters addressed to his Lordship ; three of these were republished in the Anthologia : the first dated Magilligan, June 2nd, 1725. It commences by extolling the parish as a botanical region ; “ I believe,” he observes, “ this parish could afford as good a collection of native herbs , as any one place in the three kingdomsand after enumerating some of them, adds, “ in a word, it is the physic-garden for the Irish doctors both far and near : the reason is the great variety of soil a character for botanical richness which the locality still pre¬ serves. The author also records some of the zoological rarities, such for example as a large pinna ; “ the fish is very scarce, and a non-descript ; several of the shells are nine inches long, and six inches at the broad end, and scarce half-an-inch at the other.” More than a century has elapsed, and this coast con¬ tinues a good locality for pinna fragilis ;* to obtain the fish in the valves they must be dredged up from deep water. * P. pectinata : this appears to be the common species of the Irish coast, being found in abundance both in the north and south ; the ribs are more or less spined in the young shells, but in the old the ribs are smooth ; it is fragile when young, but occasionally more massive, approximating to P. ingens ; it attains a length of eleven inches. 24 REVIEW OF THE WORKS The geological remarks refer entirely to what the author considers proofs of diluvial action in the parish of Magilli- gan. “ That this land was formerly sea,” he says “ I think, there is sufficient reason to believe, for along at the foot of the mountain, and all the coast, is the old bank to be seen, to which the sea hath formerly flowed, at the foot of which every where is sea-sand and shells to be dug up. And the Giant ’s Grave , another curiosity in this place, proves it ; it is a mile and a half long : one limb of him lies at Balspoint , at the mouth of the river Roe , passeth by Mrs . Gage ’s house, and under my house, and along the high way, a quarter of a mile farther ; it is a ridge of stones, such as the sea throws up on beaches, mixed with shells and sand ; besides, near my house, a mile from the sea, at the foot of the grave , is the quicksand raised at the second spade, and at the digging seems to be a small shell, but when some days in the air, turns to dust . The other limb of the giant , the Irish fable makes lost in a battle— but of late they have discovered some more of him, by a shell- bank under Ballycastle Orchard , two miles now from the sea up the river Roe, and another bank of shells more than a mile farther up at Skrieve , near the road from Newtown to Cole¬ raine . The low land of Magilligan is divided into ridges (or as we call them , dryms, ) of sand, from one hundred to five hun¬ dred yards broad , highest in the middle, and sloping on each side, to marshy ground (which we call misks), commonly as broad as the dryms : the dryms are generally from six to twelve feet higher than the misks ; but on the north side, next the ocean, the dryms and misks are narrower , and some of the dryms thirty or forty feet higher than the misks. Both the dryms and misks run parallel almost—first a drym , then a misk, inter¬ changeably , the whole length of the parish for five miles : the length of the dryms runs from east to west, from the mountain to Lough -Foyle , and is in most places two miles long, in some places less, in some more : only for half-a-mile, next the moun¬ tain , it is all one bog and level. The cause of this and of the lands settling in the bay , cannot otherwise be accounted for, but by the general deluge ; for I am fully persuaded that the rivers that fall into Lough -Foyle could not, with all the sand and mud that they carried down in floods, form so large a piece of country as in this parish , and Meroe , and the fiats of Bellekelly , besides OF PRECEDING WRITERS.

Load more