Table V gives the results of the computation, from our formulæ, of the calorific powers of these five gaseous mixtures, for communicating temperatures both above and below that of aqueous ebullition. We should remark that we have here been obliged to regard the volumes of illuminant hydrocarbons as representing olefiant gas solely; both because we have no certain data as to their real nature, and particularly because, if we actually knew, or should assume, the nature of the hydrocarbon vapors present, still we have no experimental calorific equivalents, as we have for olefiant gas, from which to start in such a computation. We have reason to believe nevertheless that the errors thus introduced are not important in amount.

3. Conclusions.-Some of the practical conclusions to which we are led, by the results of the above investigations, are somewhat remarkable, so that we feel diffident regarding them. It is however always safe to follow the leading of truth, however astray she may conduct us from our precon. ceived notions.

From Table II it is apparent:

1. That of all known gases, the highest calorific effects, under ordinary atmospheric conditions, are obtainable from carbonic oxyd; whose calorific value, above 100° C., is about 3000° C.

2. That, in absolute calorific value, below 100° C., in the atmospheric medium, hydrogen surpasses its volume of any other gas; giving a temperature of about 3,200° C.

3. That for all modes of application-that is, for producing both high and low temperatures-the total maximum calorific effectiveness of carbonic oxyd is a constant quantity.*

4. Compound condensed submultiple volumes of hydrogen, like that in marsh gas, have much less total calorific value in air than their volume of free hydrogen.

5. Condensed compound submultiple volumes of gaseous carbon, like that in olefiant gas, have no greater total calorific value, in air below 100° C., than their own volume of carbon gas in the form of carbonic oxyd; while above 100° C. their value is even considerably less.

ART. XXXVII.-On the Laurentian and Huronian Series in Nova Scotia and New Brunswick; by HENRY YOULE HIND, M.A.

CONTENTS:-1. Introduction; 2. General Sketch of the Distribution of the Huronian and Laurentian Series in Nova Scotia; 3. Sequence of Formations-The Upper Silurian; 4. The Lower Silurian; 5. The Gold-bearing Rocks; 6. The Cambrian or Huronian Series; 7. The Laurentian Series; 8. The Eozoon Canadense; 9. Cape Breton Island.

1. Introduction.

THE descriptions contained in this paper, so far as they relate to Nova Scotia, are in the main the results of observations during the summers of 1868 and 1869, while making geological surveys for the Nova Scotian government, in the gold districts of Waverley and Sherbrooke. The comparisons with New Brunswick are based on my official Report on the geology of that Province; and the references to Cape Breton, when not otherwise stated, are from MS. notes of explorations in that Island during 1866.

The object of this paper is to show that two gneissoid series, supposed to be the equivalents of the Huronian and Laurentian of Sir W. E. Logan, are exposed over very large areas in Nova Scotia, the Island of Cape Breton and in New Brunswick.+

The boundaries of the series have been traced through parts of Halifax, Hauts and Guysborough counties in Nova Scotia. In New Brunswick + numerous narrow belts extending from the

* Metallurgists, especially, will appreciate the suggestive import of the truth, presented under the first and third heads; here enunciated, as we think. for the first time. It is to be noted that all the above effects belong to the maximum kinds and, of course, reach their development only under the most favorable conditions in each case respectively.

Preliminary Report on the Geology of New Brunswick: Fredericton, 1865. In southern New Brunswick Prof. Bailey and Mr. Mathew have discovered and described rocks of Laurentian and Huronian age. "Observations on the Geology of Southern New Brunswick: " Fredericton, 1865. Also see an able paper by Mr. Mathew in the Journal of the Geological Society of London for 1865.

bay of Chaleurs to the boundary line between New Brunswick and Maine are supposed to represent the Laurentian and are described in my Report on New Brunswick, published in 1865 (pp. 42-52).

Geological maps of Nova Scotia were published by Dr. Abraham Gesner in 1836,* by Dr. Dawson in 1865,† and in 1868, and by Sir William E. Logan in 1865§ and in 1869.

Sir William Logan states, in the introduction to his Atlas of Maps and Sections, that for the geology of Nova Scotia "a manuscript map by Dr. J. W. Dawson, compiled from his own. resources, and those of Messrs. B. Brown and H. Poole, has been the source of information." Hence, in making the necessary comparisons between the subject of this paper and the published descriptions and maps of Nova Scotia, I shall have to refer almost exclusively to Dr. Dawson's map of 1868, accompanying the 2d edition of his beautiful work on Acadian Geology.

In a Preliminary Report on the supposed Laurentian of Nova Scotia, I have quoted some passages from Dr. Dawson's work, especially the explanation to the geological map, in which the uncertainty of the boundaries of formations, and the doubtful age of some strata, is adverted to. The recognition of a very large gneissoid area in Nova Scotia, supposed to represent two series not hitherto described as occurring in the Province, will enable some of the changes in part anticipated by Dr. Dawson to be foreshadowed with some degree of accuracy; and it is proper to repeat here Dr. Dawson's first paragraph of the "Explanations to the Geological Map": "The map in this edition, though greatly improved, is still to be regarded as merely a rude approximation to the truth, and the coloring in many places, more especially in the interior, remote from the coast lines, is little more than conjectural."

In various parts of "Acadian Geology" reference is made to rocks which were suspected by Dr. Dawson to be older than the Lower Silurian slates and quartzites. (See particularly page 620, Acadian Geology, 2d edition). These will probably now be classed with the Huronian series; and the massive porphyroid granitoid gneiss on which they rest, with the Laurentian.

Dr. Sterry Hunt visited Nova Scotia in November, 1867 "for the purpose of making some observations on the gold-bearing * Remarks on the Geology and Mineralogy of Nova Scotia: by Abraham Gesner; Halifax, 1836.

Acadian Geology, 1st edition.

Acadian Geology, 2d edition; Macmillan & Co., London, 1868.

Atlas of Maps and Sections; Montreal, Dawson Brothers, 1865.

Geological Maps of Canada and the adjacent regions, 1869: London, Edward Standford.

Preliminary Report on a Gneissoid Series underlying the Gold-bearing Rocks of Nova Scotia, and supposed to be the equivalent of the Laurentian System; Halifax, N. S., January 5, 1870.

rocks of that Province, with the view of comparing them with those of other parts of the dominion, and also of obtaining such information as might be useful in the event of a geological survey of Nova Scotia itself."

Dr. Hunt's stay in the Province was limited to four weeks in the months of November and December, and in the descriptions which he has given in his official report to Sir W. E. Logan* he quotes the following as the principal sources of information about the geology and mineralogy of Nova Scotia: Dr. Dawson's Acadian Geology, 1st ed.; Mr. Poole's Report, 1862; Mr. J. Campbell's Reports, 1862 and 1863; Professor B. Sillman's Reports on Tangier, Waverley and Montague Gold Fields, 1864.

Allusion is made in the Atlas of Maps and Sections of the Geological Survey of Canada to the opinions expressed in my Report on New Brunswick that much of the granites of that Province consist of altered sedimentary strata. "Much of what in Nova Scotia, New Brunswick and Maine, is represented on the map as intrusive rock (chiefly granite) probably consists of paleozoic strata altered in situ as already suggested by Dawson and Hind. See the latter's Report on New Brunswick, 1865, page 50." (Atlas of Maps and Sections, Geological Survey of Canada, 1865, page 20).

The remarkable similarity which exists between the rocks constituting part of the great gneissoid axis of New Brunswick and the gneissoid series now described of Nova Scotia, coupled with the equally marked similarity which obtains between the paleozoic strata resting on these gneisses in both Provinces (on. the Nipisiquit in N. B.), satisfies me that they are of the

same age.

2. General Sketch of the Distribution of the Huronian and Laurentian Series in Nova Scotia.

In this general sketch of the old gneissic rocks of Nova Scotia, they are grouped together. In succeeding paragraphs it is stated where the Huronian or Cambrian gneiss and schist rest on the old Laurentian gneiss as far as known.

The outcrop of the Laurentian and Huronian rocks in Halifax and Hauts counties, N. S., has been traced from a point seven miles west of Windsor on the Basin of Mines (Bay of Fundy) to the Atlantic coast at Cape Sambro, a distance of forty-eight miles in an air line, and sixty-four miles on the margin of the outcrop. This is the northeasterly boundary

of an immense area of the same rock series which from information hereafter noticed I believe continues with variable breadth

* Report of Dr. T. Sterry Hunt, F.R.S., on the Gold Region of Nova Scotia ; Ottawa, 1868.

to the Tusket Islands, near Yarmouth, a distance of about one hundred and thirty-five miles in an air line.

The area above described forms the western development of the Laurentian and Huronian gneisses and schists in Nova Scotia. It is separated from the eastern development by a narrow but profound valley occupied by Silurian strata, whose least breadth is eight miles. The outcrop of the southwestern boundary of the eastern development is not continuous, but embraces two areas near Grand and Fletcher's Lakes, and an area of unknown but very considerable and of variable width, stretching from Parker's Lake, with some narrow interruption of Silurian strata which have escaped denudation, probably all the way to the Strait of Canso and Chedabucto Bay, a distance of one hundred and twenty miles in an air line: so that, generally speaking, a Laurentian axis, capped here and there by strata of Huronian age, occupies Nova Scotia, certainly in one place at least forty-eight miles in breadth.

The existence in Nova Scotia of all formations from the Trias to the Laurentian, with the exception of the Permian,* may now be considered as established. Whether the rocks noticed in the foot-note are of Permian or Triassic age I am not able to say, but judging from the descriptions given of the relations of the Triassic to the Carboniferous by Dr. Dawson, I have hitherto considered small unconformable patches in Cape Breton as of Triassic age, and regarded them as the continuation of the Prince Edward Island series, resting on Lower Carboniferous rocks.

The entire series from the Lower Carboniferous downward, with the exception of the Devonian, is passed over in a journey by rail from Windsor to Halifax, in a distance of fourteen miles. The Devonian occurs at Nictau, and rest there on Upper Silurian slatest which probably sweep round the Falmouth mountains and connect with the Upper Silurian near Windsor.

3. Sequence of Formations-The Upper Silurian.

On the St. Croix river, eight miles from Windsor, the Lower Carboniferous grits are seen to rest on Upper Silurian argillites.

* In Cape Breton, at Jumping Brook, seven miles northeast of Chetican Island on the Gulf coast, and at Trout Brook, five miles northeast above Chetican, mottled sandstones and conglomerates rest unconformably on white and mottled sandstones and bituminous shales, supposed to be of Lower Carboniferous age. These latter rest unconformably, the first on red metamorphic rocks, the second are seen in close proximity to red, green, and black corrugated schists, supposed to be of Lower Silurian age. In Dr. Dawson's tabular view of the geological formations of the Acadian Provinces (page 19, Acad. Geology) the Permian is stated to be "not represented unless by the lower part of the sandstones of Prince Edward Island." May not the unconformable patches in Cape Breton be a continuation of these Prince Edward Island deposits?

Page 498 Dawson's Acadian Geology, 2d edition.