subject, it may be interesting to recal the experiments of Pelouze and Cahours on the Pennsylvanian oils, which proved to be a mixture of carbolizdrogers belonging to the marsh gas series. An elaborate exposition of Berthelot's method of transforming an organic compound into a hydrocarbon containing a maximum of hydrogen, has appeared in a connected form. The organic body is heated, in a sealed tube with a large excess of a strong solution of hydriodic acid, to the temperature of 275°. The pressure in these experiments Berthelot estimates at 100 atmospheres, but apparently without having made any direct measurements. He has thus prepared ethyl hydride from alcohol, aldehyde, &c., hexyl hydride from benzol. Berthelot has submitted both wood charcoal and coal to the reducing action of hydriodic acid, and among other interesting results, he claims to have obtained in this way oil of petroleum. By the action of chloride of zinc upon codeia, Matthiessen and Burnside have obtained apocodeia, which stands to codeia in the same relation as apomorphia to morphia, an atom of water being abstracted in its formation. Apocodeia is more stable than apomorphia; but the action of reagents upon the two bases is very similar. As regards their physiological action, the hydrochlorate of apocodeia is a mild emetic, while that of apomorphia is an emetic of great activity. Other bases have been obtained by Wright by the action of hydrobromic acid on codeia. In two of these bases, bromotetracodeia and chlorotetra-codeia, four molecules of codeia are welded together, so that they contain no less than seventy-two atoms of carbon. They have a bitter taste, but little physiological action. The authors of these valuable researches were indebted to Messrs. Macfarlane for the precious material upon which they operated. We are indebted to Crum Brown and Fraser for an important work on a subject of great practical, as well as theoretical, interest—the relation between chemical constitution and physiological action. It has long been known that the ferrocyanide of potas sium does not act as a poison on the animal system; and Bunsen has shown that the kakodylic acid, an arsenical compound, is also inert. Crum Brown and Fraser found that the methyl compounds of strychnia-brucia and thebaia are much less active poisons than the alcoloids themselves; and the character of their physiological action is also different. The hypnotic action of the sulphate of methyl-morphium is less than that of morphia. But a reverse result occurs in the case of atropia, whose methyl and ethyl derivatives are much more poisonous than the salts of atropia itself.

THE POST PLIOCENE GEOLOGY OF CANADA,

BY J. W. DAWSON, LL.D., F.R.S., F.G.S.

PART II.-LOCAL DETAILS.

Before entering into the special consideration of this Second Part of the subject, I desire to call attention to some additional facts bearing on two of the most remarkable properties of the Post-pliocene deposits of the Northern Hemisphere, namely their general similarity of arrangement, and their local diversities.

In the first part of this memoir, taking the Post-pliocene of the Lower St. Lawrence as a type, I showed that it has its parallel, with but slight general difference, in the wide-spread superficial deposits of the interior of North America surrounding the great lakes, and that the Post-pliocene deposits of Scotland and Scandinavia almost precisely resemble those of Canada in the general sequence of deposits. Since that part was published, additional illustrations have been afforded by papers in the Geological Magazine by Mr. Hull, and Mr. Mackintosh, by papers and discussions on the Eskers of Ireland, at the meeting of the British Association, and by an able monograph on the Estuary of the Forth, by Mr. David Milne Home. Mr. Hull, who is a "Land Glacialist," arranges the deposits of the Drift Period in the British area in the following three groups, in descending order, in accordance with Prof. Ramsay's observations in England, and his own in Ireland.

1. Upper Boulder-clay, which he regards as "generally marine." In Canada, this is represented by the loose boulders and partial boulder deposits of the Upper Saxicava Sand.

2. Shelly marine sands and gravels belonging to the greatest depression of the land, and representing our Saxicava Sand and Leda Clay.

3. Lower Boulder-clay, which represents the true or principal Boulder-clay of Canada. This Mr. Hull attributes "chiefly to land ice."

In Ireland, it would thus seem that the principal sub-divisions of the Post-pliocene can be recognized, and Mr. Kinahan has described the remarkable ridges of gravel called eskers which run

across the country in a North-east and South-west direction. Like our Canadian eskers or "Boar's backs," they are now admitted to be of marine origin, and are attributed to current action and to the waves, though floating ice has no doubt, as in Canada, contributed in some cases to their formation.

Mr. Milne Home gives a graphic description of the Post-pliocene deposits in the neighbourhood of the Frith of Forth, and many of his numerous sections might have just as well been taken from Canadian deposits. He thus sums up the causes of the phenomena, assuming that at the beginning of the period the land was submerged.

"The ocean over and around Scotland was full of icebergs and shore ice, which spread fragments of rocks over the sea bottom and often stranded, ploughing through beds of mud, sand, gravel, and blocks of stone, and mingling them together in such a way as to form the Boulder-clay.' The land thereafter gradually emerged, during which time the long ridges or embankments of gravel called 'kames' were formed."

Mr. Mackintosh's observations go mainly to show that in England, as in Canada, even the lower drift and rock striation are due to a great extent to floating ice and not to glaciers, and he extends this conclusion even into the lake district of England.

It is also worthy of remark that the long-received doctrine that glaciers are powerful eroding agents, which the author showed in a paper in this journal, in 1866, to be without foundation, is only now beginning to be discredited in England. I shall refer to this in the sequel, and in the meantime may direct attention to an interesting paper on the subject by Mr. Bonney, F.G.S., in the Journal of the Geological Society for August, 1871.

It would further appear that, after the glacial period, in the Post-glacial, the British land rose to a level higher than that which it at present exhibits, then sunk again, and re-emerged in the modern period. Evidences of this later submergence have not been recognized in Canada, but in the inland area they have been detected by Hilgard and by Andrews.

Since the publication of the first part of this memoir, Prof. Hilgard has discussed the subject of the southern drifts of the Mississippi valley at the meeting of the American Association at Indianapolis; and I am indebted to that gentleman and to Prof. Andrews, of Chicago, for much information on these deposits and their relation to those of more northern regions.

It appears that the oldest Post-pliocene deposit in the south is that called by Prof. Hilgard the "Orange Sand." This deposit is spread over the States of Mississippi, Alabama, Tennessee, and parts of Louisiana, Kentucky, and Arkansas, and in some places attains an elevation of 700 feet. It contains water-worn fragments of northern rocks, and is supposed by Prof. Hilgard to have been deposited by rapid currents of water, possibly fresh, as the deposit contains no marine fossils.

Above this, according to Prof. Hilgard, is found in places a swamp, lagoon or estuary formation designated the "Port Hudson group." Succeeding this is the "Bluff or Loess" group, a deposit of fine silt, limited almost or entirely to the Valley of the Missisippi. Its maximum thickness is seventy-five feet.

On this rests a very widely distributed bed, the "Yellow Loam," not more than twenty feet thick, but much more extensively distributed laterally than the former, and reaching an elevation of 700 feet.

Under the names of "Second Bottoms or Hummocks," and "First Bottoms," are known terraced deposits of clay belonging to the present river valleys, but indicating in the case of the Second Bottoms a greater amount of water than at present.

It is obvious that all of the above are aqueous deposits, and there seems to be no evidence whatever in the region referred to, of the action of land ice, though the stones and few boulders in the Orange sand are very probably due to floating ice. There seems reason to believe that the Orange sand is continuous with the Boulder-drift of the north-west; and if this is, as stated by Newberry and others, a later deposit than the Erie clay, then it is probable that no representative of the latter exists to the southwest, or that the Orange sand represents the whole of the northern deposits. In any case it represents northern currents of water, though whether salt water admitted by the depression of the land, or fresh water resulting from the melting of glaciers, it is not easy to decide, as very great difficulties attend either view in the present state of our knowledge of the deposit. Whatever the conditions of deposit of the Orange sand, it would seem to have been succeeded by a land surface, and this by a depression to the extent of 700 feet or more, before the modern elevation of the land. If this last elevation corresponds with that of the terraces of the St. Lawrence, then the former one must have occurred in the St. Lawrence valley in the interval

between the deposit of the Leda clay and the close of the Postpliocene. This question we shall have occasion to consider in the sequel, in connection with the second depression of the European land above referred to.

Since the publication of the first of these papers, Dr. Newberry has kindly sent me a paper of his published as early as 1862, in which he states the remarkable fact, quoted above from his more recent Report on Ohio, that the drainage of the great lake basins, open in the early Post-pliocene period, was obstructed by the glacial deposits, and has been only partially restored. He also desires me to state that he refers the old drainage not exclusively to the action of glaciers, but to the "ice period, or an earlier epoch." I am happy to make these corrections; the latter more especially, as it brings our theoretical views more into harmony. Dr. Newberry, however, for whose conclusions on such subjects. I have the highest respect, still, in his latest expressions of opinion, adheres to the action of land ice in producing the glacial striation, which from his descriptions is, I should suppose, quite as definite and strongly marked as that in the St. Lawrence valley.

The grand series of Post-pliocene changes was thus uniform in Europe and America, pointing to great general causes of subsidence and re-elevation; but locally there is the most extreme irregularity in these deposits, giving great uncertainty to their arrangement. Some of these differences we shall have occasion to notice under the following geographical subdivisions.

1. Newfoundland and Labrador.

In the Journal of the Geological Society of London, for February, 1871, is a communication from Staff-commander Kerr, R. N., of the Coast Survey, in which he gives the directions of twentyeight examples of grooved and scratched surfaces observed in the southern part of Newfoundland. The course of the majority of these is N.E. and S.W., ranging from N.8° E. to N. 64° E. The remainder are N.W. and S.E., most of them with a predominating Easterly direction. Boulders are mentioned, but no marine beds. The author refers the glaciation to land ice, supposing certain submerged banks across the mouths of the bays to be terminal moraines.

The latest information on the Post-pliocene of Labrador is that given in a paper by Dr. Packard in the memoirs of the Boston Society