had altogether retired from its bed; and the distant channel appears as a mere stripe of muddy water. At the commencement of flood, a slight ripple is seen to break over the edge of the flats. It rushes swiftly forward, and, covering the lower flats almost instantaneously, gains rapidly on the higher swells of mud, which appear as if they were being dissolved in the turbid waters. At the same time the torrent of red water enters all the channels, creeks, and estuaries; surging, whirling and foaming, and often having in its front a white, breaking wave, or "bore," which runs steadily forward, meeting and swallowing up the remains of the ebb still trickling down the channels. The mud flats are soon covered, and then, as the stranger sees the water gaining with noiseless and steady rapidity on the steep sides of banks and cliffs, a sense of insecurity creeps over him, as if no limit could be set to the advancing deluge. In a little time, however, he sees that the fiat, "hitherto shalt thou come and no farther," has been issued to the great bay tide its retreat commences, and the waters rush back as rapidly as they entered.

The rising tide sweeps away the fine material from every exposed bank and cliff, and becomes loaded with mud and extremely fine sand, which, as it stagnates at high water, it deposits in a thin layer on the surface of the flats. This layer, which may vary in thickness from a quarter of an inch to a quarter of a line, is coarser and thicker at the outer edge of the flats than nearer the shore; and hence these flats, as well as the marshes, are usually higher near the channels than at their inner edge. From the same cause, the more rapid deposition of the coarser sediment, the lower side of the layer is arenaceous, and sometimes dotted over with films of mica, while the upper side is fine and slimy, and when dry has a shining and polished surface. The falling tide has little effect on these deposits, and hence the gradual growth of the flats, until they reach such a height that they can be overflowed only by the high spring tides. They then become natural or salt marsh, covered with the coarse grasses and carices which grow in such places. So far the process is carried on by the hand of nature; and before the colonization of Nova Scotia, there were large tracts of this grassy alluvium to excite the wonder and delight of the first settlers on the shores of the Bay of Fundy. Man, however, carries the land making process farther; and by diking and draining, excludes the sea water, and produces a soil capable of yielding for an indefinite period, without manure, the most valuable cultivated grains and grasses. Already there are in Nova Scotia more than forty thousand acres, of diked marsh, or "dike," as it is more shortly called, the average value of which cannot be estimated at less than twenty pounds currency per acre. The undiked flats, bare at low tide, are of immensely greater extent.

The differences in the nature of the deposit in different parts of the flats, already noticed, produce an important difference in the character of the marsh soils. In the higher parts of the marshes, near the channels, the soil is red and comparatively friable. In the lower parts, and especially near the edge of the upland, it passes into a gray or bluish clay called "blue dike," or, from the circumstance of its containing many vegetable fragments and fibres, "corky dike." These two varieties of marsh differ very materially in their agricultural value. It often happens, however, that in the growth of the deposit, portions of blue marsh become buried under red deposits, so that on digging, two layers or strata are found markedly different from each other in color and other properties; and this change may be artiâcially produced by digging channels to admit the turbid red waters to overflow the low blue marsh.

The red marsh, though varying somewhat in quality, is the best soil in the province, and much of it compares favorably with the most celebrated alluvial soils of the old and new worlds. The following analysis of recently deposited marsh mud from Truro, will serve to show the composition of this kind of soil.

So valuable is this soil, though nearly destitute of organic matter, that it is found profitable to cart it upon the upland as a manure. Its best varieties have now been cropped without manure for more than two centuries without becoming unproductive; though there can be no question that under this treatment a gradual diminution of its fertility is perceptible. The weakest point of the marsh land, judging from the above analysis, is its small proportion of phosphates. It is probable, however, that this is in part compensated by the presence of fish bones and other matters of organic origin, which do not appear in an analysis. Yet I have no doubt that the cheapest manure for failing marsh will be found to be bone dust or guano, which, by supplying phosphates, will restore it nearly to its original con. dition. There seems no reason to suppose that a soil with the fine mixture of mineral ingredients present in the marsh mud, requires any artificial supply of ammoniacal matters. Draining is well known to be essential to the fertility of the marshes, and many valuable tracts of this land are now in an unproductive condition from its neglect. The fertility of failing marsh may also be restored by admitting the sea to cover it with a new deposit. This remedy, however, involves the loss of several crops, as some years are required to remove from the new soil its saline matter. It is, however, observed, that in some situations the newly diked marsh produces spontaneously a crop of couch grass and other plants, the seeds of which must have been washed into the sea by streams and deposited with the mud. The low or inner marsh, which I have previously mentioned, under its other names of blue marsh and corky dike, is much less valuable than the red. It contains, however, much more vegetable matter, and sometimes approaches to the character of a boggy swamp; so that when a quantity of it is taken out and spread over the upland, it forms a useful manure. It emits a fetid smell when recently turned up, and the water oozing from it stains the ground of a rusty color. It produces in its natural state crops of coarse grass, but when broken up is unproductive, with the sole exception that rank crops of oats can sometimes be obtained from it.

The chemical composition of this singular soil, so unlike the red mud from which it is produced, involves some changes which are of interest both in agriculture and

geology. The red marsh derives its color from the peroxide of iron. In the gray or blue marsh, the iron exists in the state of a sulphuret, as may easily be proved by exposing a piece of it to a red heat, when a strong sulphurous odour is exhaled, and the red color is restored. The change is produced by the action of the animal and vegetable matters present in the mud. These in their decay have a strong affinity for oxygen, by virtue of which they decompose the sulphuric acid present in sea water in the forms of sulphate of magnesia and sulphate of lime. The sulphur thus liberated enters into combination with hydrogen, obtained from the organic matter or from water, and the product is sulphuretted hydrogen, the gas which gives to the mud its unpleasant smell. This gas, dissolved in the water which permeates the mud, enters into combination with the oxide of iron, producing a sulphuret of iron, which, with the remains of the organic matter, serves to color the marsh blue or gray. The sulphuret of iron remains unchanged while submerged or water-soaked; but when exposed to the atmosphere, the oxygen of the air acts upon it, and it passes into sulphate of iron or green vitriol,—a substance poisonous to most cultivated crops, and which when dried or exposed to the action of alkaline substances, deposits the hydrated brown oxide of iron. Hence the bad effects of disturbing the blue marsh, and hence also the rusty color of the water flowing from it. The remedies for this condition of the soil are draining and liming. Draining admits air and removes the saline water. Lime decomposes the sulphate of iron, and produces sulphate of lime and oxide of iron, both of which are useful substances to the farmer.

This singular and complicated series of processes, into all the details of which I have not entered, is of especial interest to the geologist, as it explains the causes which have produced the gray color and abur.dance of sulphuret of iron observed in many ancient rocks, which like the blue marsh have been produced from red sediment, changed in color from the presence of organic matter. It also explains the origin of those singular stains, which, in rocks colored by iron, so often accompany organic remains, or testify to the former existence of those which have passed away."

In Nova Scotia, as in Canada, a wide break in the geological scale, occurs below the drift, although of a less extensive character than with us. Two formations--one of vast importance-absent in Canada, are there met with. These are the Permian (?) and the Carboniferous formations: the latter occupying in New Brunswick and Nova Scotia proper, a wide extent of territory. Devonian and, without doubt, Silurian strata likewise occur there; but the beds of these epochs are in general much disturbed, and rendered metamorphic by igneous action. From their less altered positions, however, numerous fossils have been collected, some of which are figured in the present work. The occurrence of still older metamorphic rocks, chiefly associated with the granites of the Atlantic coast, is also shewn to be exceedingly probable.

Much doubt at one time existed as to the true age of the red sandstone strata of these regions. Sir Charles Lyell was the first to prove that a considerable portion belonged to the Lower Carbonife

rous period. Satisfactory proofs of the posterior age of another portion, are entirely due to Mr. Dawson's researches. The only debateable point that remains for future elucidation, affects the question as to whether these newer strata belong to the Permian or to the Triassic epoch. The author's opinion referring them to the former, is probably the correct one. In Nova Scotia, this upper formation is chiefly limited to the inner coast of the Bay of Fundy; but it appears to occupy, on the other hand, the entire area of Prince Edward's Island. At Walton, near the mouth of the Shubenacadie, N. S., Mr.Dawson met with it resting in slightly inclined beds on the upturned edges of the lower strata; and he gives in his book, from one of his earlier papers communicated to the Geological Society, an exceedingly interesting section illustrative of this want of conformability between the two formations. The new red sandstone in Nova Scotia is every where traversed by extensive outbursts of trap belonging to the same geological period. Cape Blomidon, Cap d'Or, and other bold and picturesque headlands of the Bay of Fundy, are thus constituted. These trap localities offer to the mineralogist a rich harvest of zeolitic and other specimens. As in the older trap of Lake Superior, native copper is also present, but in comparatively small and unimportant quantities. Following Dr. Jackson and others, Mr. Dawson attributes the origin of the copper to deposits from solutions by electro-chemical action: although he states at the same time, "why this deposit should have occurred in trap rock does not appear very obvious"; and, furthermore-"when we take a piece of native copper from Lake Superior or Cap d'Or, with the various calcareous and silicious minerals which accompany it, nothing can be more difficult than to account on chemical principles for these assemblages of substances, either by aqueous or igneous causes." There can be no doubt that the precipitation of metallic copper by natural voltaic agencies is a phenomenon of actual occurrence; and, looking, amongst other circumstances, to the small amount of copper present in the trap of Nova Scotia, we might be justified, were further considerations kept out of view, in adopting the author's conclusions for that particular locality. But, with regard to the origin of the Lake Superior copper, occurring in such vast and apparently inexhaustible masses in the more ancient trap of that district, we hold the opinion of Agassiz and other observers, to be the true one, viz.—that, like the igneous rock with which it is so intimately blended, the copper is itself of igneous origin. If we allow the copper to be an igneous product, its occurrence in these igneous rocks of different geological ages, and in widely-remote localities-as in the Silurian trap of Lake Superior, the Triassic or

Permian trap of Connecticut, New Jersey and other States of the Union, in the same trap of Nova Scotia, of Baumholder in Rhenish Prussia, &c., becomes clearly intelligible; whilst, on the electrochemical theory, its connection with this igneous rock, as truly stated by Mr. Dawson, is without any obvious explanation. This alone would be a strong argument in favor of its igneous origin; and when we consider the enormous amount present in the Lake Superior trap, and the absence of secondary products, such as must have resulted from the precipitation of this immense volume of metal from an aqueous solution, the case becomes still further strengthened. The only real objection to the igneous view, arises from the presence of zeolites and calc-spar, often in the closest association with the copper. Allowing the zeolites present in most traps, to be, as a general rule, after or secondary products arising from a decomposing process in the trap itself, we cannot obviously apply this argument to the copper. We know furthermore that many basalts-tough and unweathered-actually contain both zeolites and carbonates as constituents of their mass. That such constituents, moreover, cannot in all cases at least, be the result of alteration and decomposition, is plainly proved by the presence of metallic iron in certain basalts, as shewn by the interesting researches of Dr. Andrews. Nay, our author himself, in a very able discussion of the facts connected with the formation of the iron veins of the Cobequid Hills, assigns to ankerite-a compound of the isomorphous carbonates of lime, protoxide of iron, and magnesia-an eruptive or igneous origin. His views, in this respect, may not meet the approbation of all geologists, but we regard them as perfectly legitimate. An extensive examination of very numerous specimens of vein-stones and mineral aggregations, with particular reference to this question, has established in our mind the firm conviction that carbonate of lime does at times undoubtedly originate, or crystallize, from a directly igneous source. Indeed, all modern researches tend to shew, that there exists in nature scarcely a single mineral substance which is not sometimes produced by aqueous and sometimes by igneous agencies. With regard to the occurrence under particular conditions of hydrated minerals and carbonates in trap rocks, we may call to mind that volumes of steam and emanations of carbonic acid are largely given off from modern lavas, not immediately after their transmission from the volcanic orifice, but so soon as their temperature has cooled down below a certain point. If, by various readily-conceivable causes, the emission of these products be prevented, the formation of hydrated and carbonated compounds becomes a necessary result. In certain Etnean lavas, known by the somewhat loosely-applied term of Cyclo