they are connected to a fundamental rock, by their lower edges, as is represented in Fig. 3. of the same plate. In endeavouring to ascertain the relation of strata of the primitive class, when no fundamental rock is to be detected, we must endeavour to trace their course, from one unstratified rock to another; each of which they may meet at various angles. (This is intended to be shewn in the plate on the title-page of this essay.) There is again another relative position of rocks. We may conceive of the surface formed by the upper edges or outgoings of any set of strata, as affording a foundation for stratified or unstratified masses of a newer formation.

In explanation of the phenomena connected with the inclination of strata, nothing satisfactory has yet been written. Primitive rocks, that have no relation of superposition to other masses, exhibit all varieties of position, from the vertical to the horizontal; although the inclinations of 45° to 70° with the horizon, are perhaps the most prevalent. The angle of inclination observed by transition rocks, and the older sandstone, is often from 20° to 35°, but much less in still newer rocks. Frequently strata are vertical, when on some preconceived hypothesis they ought to have been horizontal; and the amazement that is daily expressed by geologists, on witnessing such displays, is as unaccountable as the pertinacity with which theories are adhered to, that are perpetually at variance with existing facts. Mr GREENOUGH, in explanation of some of these anomalous appearances, submits a question, “If corpuscular attraction, that agent by which our tea-kettles are furred, and decanters coated, has not acted on the formation of veins and strata?" The subject is involved in the greatest obscurity.

The disturbances which have given rise to the inclination of strata are, however, often connected with the presence of dikes and veins, and a proximity to unstratified rocks. Indeed, from the chemical views entertained in this essay respecting the formation of terrestrial matter, this phenomenon is what ought to have been expected. The causes that have influenced the polyedrous arrangement of the particles constituent to unstratified masses, seem to have often destroyed the stratified arrangement of the rocks that are contiguous to them. The Huttonians wish to refer the cause of disturbance among strata, to igneous matter ejected from below. This notion is in most instances highly questionable; but it is by no means unlikely, that, under the form and nature of the inflammable bases of earthy matter, many mountain-masses which belong to trap districts, might have been elevated from depths far below the present crust of the earth. But as for granitic rocks, and the strata associated with them, there is no evidence of any such circumstances of origin, since the felspar does not shew the test of vitrification displayed in districts of undoubted volcanic origin.

Regarding the curvatures of strata, nothing satisfactorily has yet been advanced. They appear to be assignable to mechanical causes, occurring during the deposition of earthy matter, from a state of solution or suspension.

These are most of the remarks I have to offer on the Phenomena of Stratification, and the principles on which a Geological Survey of Shetland will be conducted. It is, therefore, now time to abandon the speculations of the closet, and to survey Nature as she appears in a country that affords every facility for examination, owing to the naked rocks that are revealed along the shores of the numerous inlets of the sea, by which these islands are intersected in every direction. "Ite, Filii," says WALLERIUS to his pupils, "emitte calceos, montes accedite, valles, solitudines, littora maris, terræ profundos sinus inquirite; mineralium ordines, proprietates, nascendi modos notate: tandem carbones immitte, fornaces constructe, et sine tædio coquete; ita enim ad corporum proprietatumque cognitionem pervenietis; alias non."

ago or more.

[Before describing the islands of Shetland, I find that it will be necessary to say a few words respecting the numerous Names under which the group of islands to be treated of, has been known. AGRICOLA Saw Shetland from the shores of Orkney, and gave it to the name of Thule; (Dispecta est et Thule); an appellation that was applied to other northern countries, of which the Romans had little information. The oldest specific name, however, which has been given to the country is to be found in the Orkneyinga Saga; it is also used by TORFEUS, in his Orcades, in preference to any other term. "Hialtlandia vel Hiatlandia," says this author," prisco sermone semper usurpatur an a capulo gladiorum, qui hiallt appellatur, demoninata sit incolae viderint." From Hialtland arose the corruption of Yealtaland-,the name that the natives gave to their country a century This appears to have been shortened by the Scottish settlers into Yetland, under which appellation the country is described in some old documents given in Mr PETERKIN's collection of feudal papers belonging to Orkney, as well as in page 31. of Sir ROBERT SIBBALD'S description of Shetland. The transition of Yetland into Zetland, was in Scotland a very easy one, for, as Dr KEMP has remarked on the word, "The Z in the ancient Scottish dialect, and still in vulgar pronounciation, sounds like Y; witness Mackenzie, Menzies, pronounced by the vulgar Mackenyie, Menyies." Dr CHALMERS, however, supposes that Zetland was a name given to these islands by the ancient rovers, (from the German, zetten, spargere, dispergere,) significant of dispersed or separated islands; but I doubt, in the present instance, the propriety of this etymology. Another name (known to TORFEUS) that has been allotted to them was Hetland, signifying the high or lofty land. I may observe, that Norwegian writers say, that Shetland is a corruption of this word.

There are many provincial terms derived from the Norse, that are in common use to denote the various appearances of land and water. These will be explained in the course of this work, though not with the accuracy that might be expected from one who is versed in the language of the North. It may be also remarked, that, since the ancient language of the country has undergone a change from Scottish settlers, many terms of discrimination appear to have been lost. Thus, it is probable, that an inlet of the sea was named a fiord or firth, and a small creek that might occur in it a voe; but at the present day, there is no distinction of this kind].