descended from the Southern Alps in Postpliocene times. The present rivers have invariably excavated their courses in them; and the swell of the ocean, having a northerly direction, has connected the more advanced portions together by forming a dam of sands, behind which estuaries and lagoons of greater or less extent have been formed, washing the western foot of those morainic accumulations which have not advanced so far. The headlands are those portions of the moraines in which the greatest number of large blocks are enclosed; in fact they correspond generally with the central and lateral moraines.

At the same time a partial destruction of these headlands has offered the means for their further protection by raising at their base huge masses of rocks, which extend into the sea for a considerable distance, and against which the waves break furiously but ineffectually; whilst the softer beds between them, which have not this protecting talus, are, if not constantly, at least during the frequent gales along this coast, quite unprotected from the fury of the waves, and are much less able to withstand their destructive power.

Some of the imbedded blocks are of enormous size, often larger than the celebrated Pierre-à-bot in the Jura. One of the most striking examples is the large block lying in front of the centre of the Baldhead moraine, to which it owes, without doubt, in some degree its preservation. This block, which consists of contorted clay-slate with layers of quartz, is from 30 to 40 feet in diameter, and covered on its summit with a luxuriant vegetation.

It is instructive to observe the manner in which the huge blocks, when washed from the cliffs, or fallen from above when any portion of the latter has been undermined by the waves, are soon buried, in many places, in the marine sand which the southerly swell brings incessantly along with it. These blocks, if not too large, will very often sink considerably during one tide, the sand below and around them being washed away, whilst another tide covers them up entirely with sand left behind. Thus it will often happen that their angles remain quite sharp after their burial in the sand, and are thus preserved from further abrasion. But the upper portions of many of the larger blocks remain uncovered, and are thus exposed to the fury of the waves for a considerable time; but, owing to their extreme hardness, their angles become less rounded than might have been expected. Of course there are many blocks which have not only their edges worn off, but present that perfectly smooth appearance so peculiar to rocks lying in the tidal way.

These recent marine accumulations, in which former glacier-deposits are imbedded in marine sands with marine mollusks and other exuviæ, lead me to offer the following observations suggested by a contemplation of this phenomenon.

There is no doubt that, at least in some portions of the west coast, the land is sinking rapidly, a conclusion repeatedly forced upon me in passing the remains of forests now standing below high-watermark. Should this western side sink about 800 feet more by further geological changes, by far the greater portion of these moraines

Jackson Head.

Stafford Bay.

Big Bay.

ru'a

would be destroyed, the large blocks would bcome imbedded in true marine sands, with shells of mollusks now inhabiting our western shores, either entire or in broken pieces, bones of cetaceans, fishes, and remains of plants occurring between.

The land rising again, the drainage-channels cut through the marine deposits, would offer sections of a very curious structure; and there is no doubt that in many instances the conclusion arrived at would be, that these extensive beds were of glacial origin, deposited by icebergs, and that the fossil flora and fauna imbedded in them belonged to a much colder climate than that which existed in reality when these beds were deposited.

It struck me at the same time that many beds in the northern hemisphere which are called glacial, are probably similar beds rearranged; and that many apparent difficulties will disappear if such a process is taken into consideration. Furthermore may we not assume that at least some of these beds in older formations, in which similar rounded and sharp-edged blocks are associated together, have a similar origin?

In any case the formation of these recent marine beds from the destruction of Postpliocene accumulations is highly suggestive to the physical geologist; and deductions drawn from such observations may claim some consideration at the hands of those who are attempting to account for the various characteristic features of the glacial beds in the northern hemisphere.

If we examine the structure of the large moraines under consideration, and the lithological character of the rocks imbedded in the débris, some important facts are revealed to us, to which I beg to draw your special attention.

In my short explanation of the structure of the Southern Alps, I have pointed out that their very summit consists of dioritic sandstones, cherts, &c., and that towards the west they are immediately underlain by the newer gneissic schists, below which follow mica-schists &c., until the gneiss-granites which form the base of the Southern Alps are reached.

This peculiarly regular succession of the strata according to age and metamorphic change, from east to west, assists us, when we examine the débris of which the huge Postpliocene moraines consist, to obtain a clear conception of the extent, breadth, and other conditions of the huge glaciers to which they owe their existence. Thus we observe, as there is no débris of truly metamorphic rocks amongst the component parts of these enormous deposits, but only diorite-sandstones, felstones, true clay-slates, and other similar rocks which form the summit of the central Alps of the present day, that the height of land was the same in the glacial epoch as it is now. In fact, the present huge glaciers on the eastern slopes of the central chain are covered with débris of the same lithological character as that of which the Postpliocene moraines along the west coast are composed. The total absence of true mica- and chlorite-schists, gneiss, and gneissic granite, which form the western foot of the ranges under consideration, as well as of the granite and sericite

slates which constitute the isolated low wooded cones or ridges rising at present above the morainic accumulations, suggests at once that the whole country was uniformly covered with one continuous sheet of ice, grinding and planing down the whole lower region in a remarkable degree. And, if we go further, may we not assume that the enormous triturating power by which the auriferous beds were ground down to nearly their present outline, may in some degree account for the presence of the fine dust-like gold found in large quantities along the shores of that coast for several hundreds of miles?

The older alluvial beds, lying, in several instances, upon these morainic accumulations, show convincingly, when their contents are examined, that at the time they were deposited a great change in the relative position of the Alpine glaciers had taken place.

Although many rolled boulders from the very summit of the central chain may still be collected amongst them, derived either from the younger moraines of the smaller glaciers, or from the older moraines through which their outlet had cut a passage, we find that the metamorphic schists and gneiss-granite of the Southern Alps proper, and the newer granites and syenites of the hills in front, are also well represented. Such a total change in the nature of the beds proves convincingly that the glaciers have not only retreated considerably, but have now formed distinct channels on the lower slopes of our Alps, the streams issuing from them being able to bring down the débris from the granite bosses in front.

These Postpliocene river-beds, of such distinct lithological character, mostly repose upon, or occur near the moraines. But there is one instance, in Boldhead, which at first sight seems to indicate that at least one oscillation occurred during the glacier-epoch, during which the Boldhead glacier must have retreated so considerably as to bring the lower metamorphic and hypogene rocks within the denuding action of its outlet. These interesting fluviatile deposits consist of beds of sedimentary and semimetamorphic rocks, which form the morainic accumulations of well-rounded boulders of granite, gneiss, and metamorphic schists, which, during the great glaciation of the country, were covered uniformly by a sheet of ice. In fact, these Postpliocene fluviatile beds cannot be distinguished from the present river-beds of the same region, except by the somewhat larger size of their blocks of stone.

At first sight it thus appears that such a considerable change has taken place during the glacial epoch that the Boldhead glacier could retreat at least ten miles, so as to uncover the coast-ranges, which, although in that neighbourhood from 3000 to 4000 feet high, have the peculiar rounded forms of true roches-moutonnées. But as signs of such enormous oscillations are nowhere else discernible, a second explanation may be more correct-namely that the alluvial riverbeds were deposited by the river Mikonui, which enters the sea a few miles north, during a slight oscillation of the Boldhead glacier. There occur also in Boldhead, and in some other cliffs further south, very large deposits, consisting of the finest glacier-mud, which are

often stratified in such thin layers that many hundreds of them go to the inch, and which were without doubt formed in lakes amongst huge ice-masses.

In ascending from the level of the sea to the slopes of the Southern Alps there are many sections in the banks of the river which show well the gradual retreat of the Postpliocene glaciers; in some other localities, on the other hand, there is ample evidence offered to us that there has been an advance of the glaciers during more recent times, since the broad river-beds were formed. Thus, to give only one instance, three miles from the present terminal face of the Francis Joseph glacier, we meet a moraine curving across the shingle-bed of the Waiau river, which is here more than a mile wide, and by which this newer moraine has been destroyed in many spots, through which its structure has become visible. An examination of these beds reveals the important fact that the channel of the Francis Joseph glacier was cut deeply into the ranges during their deposition, as we find many blocks of truly metamorphic rocks mixed up with those derived from the summit of the Southern Alps. Finally, I beg to point out that glacier-lakes are not altogether missing on the western side of the Southern Alps proper: a few of them, like lakes Brunner and Kanieri, are dammed up by enormous morainic accumulations; others, from the descriptions given to me by trustworthy miners, appear to be true rock basins, some of which I hope to visit in the course of next autumn.

7. On the CHEMICAL GEOLOGY of the MALVERN HILLS.
By the Rev. J. H. TIMINS, F.G.S., M.A.

In the year 1861, I commenced an examination of the rocks composing the Malvern Hills; and the results of the analyses of some of the eruptive rocks, taken from various parts of the chain, were published in the Edinburgh New Philosophical Journal, vol. xv. pp. 1-7. Since then, a minute and accurate description of the structure of these hills has been given by my friend Dr. Harvey B. Holl (Quart. Journ. Geol. Soc. vol. xxi. p. 72), to which I shall have to refer, in the course of this paper, for a more particular account of the physical geology of the district under investigation. I have also had the advantage of visiting the hills with him, and, with his assistance, I have been able to make many valuable additions to my collection of specimens of the various rocks for analysis.

In the present communication I propose to examine the rocks with a view to the discovery of the sources from which they have been derived, and the chemico-physical processes which have resulted in their development, confining myself more especially to the consideration of those which appear to be, wholly or in part, the products of eruptive action, whether they occur as intrusive masses, lava-flows, or beds of ash mechanically deposited. Those of which the materials were originally furnished by the decomposition and disintegra