clay with which they are covered may have been washed down from the hills above them. The loess may be traced all round the flanks of the hills that surround the great plain between Basel and Bingen, and also on the hills that in some places rise up like islands in its midst. Thus Sir Charles Lyell notes that it covers, up to a height of 1600 feet above the sea, the Kaiserstuhl, -a volcanic hill which stands in the middle of the great valley of the Rhine, near Freiberg, in the Brisgau. It is also spread over the volcanic hills of the Lower Eifel. Dr. Samuel Hibbert, in his " History of the Extinct Volcanoes of the Basin of Neuwied on the Lower Rhine," published in 1832, gave many instances of the intercalation of the loess. with beds of volcanic ashes near Andernach. Much white. pumice is spread over the loess, and it seems to be well ascertained that both during its deposit and afterwards the volcanoes were active. The veteran geologist, Herr Henry von Dechen, has mapped out these deposits, and described them in his "Geognostischer Fichrer zu dem Laacher." He has informed me that one of the highest patches of the loess on the volcanic hills lies south of Andernach, near the hill of Korrets, at an altitude of about 620 feet. Dr. Hibbert appears to have found it higher, for he states that on the Mahlsberg the loess attains an elevation of 800 feet above the sea, or 600 feet above the river, and is sometimes 60 feet thick. With regard to the pumice that is abundantly spread out on the top of the loess between Andernach and Coblentz, and which Herr von Dechen informed me indicated that the volcanoes were active at the time of the close of the deposition of the loess, it may be worth remarking that the Challenger explorations have shown that great quantities of pumice are spread over the bed of the ocean, proving it to be a common product of submarine volcanoes; so that it is quite in accordance with our knowledge of its production to suppose that the volcanoes of the Eifel at the time of its eruption may have been submerged beneath the waters from which the loess was deposited. The loess extends up the valleys of the tributaries of the Rhine. The basin of the Neckar is, according to Sir Charles Lyell, filled with it. It is of great thickness, and at Canstadt, near Stuttgart, overlies a bed of gravel, and contains bones of the mammoth and the woolly rhinoceros. There are thick deposits of loess in the valley of the Main. I had the great advantage of examining it near Wurzberg, in the company of the celebrated geologist Dr. Sandberger. It has been principally preserved, from the effects of great floods that appear to have swept down the valley, in bays and recesses, and at these points bones of the mammoth and its associates have been found. I took the following section (Fig. 2) at Blosenberg, near Heidingsfeld, where the loess is extensively dug for brick-making. At the clay-pit the lowest bed seen is one of subangular quartzose gravel, with pebbles of crystalline rocks from the mountains at the sources of the Main. This is covered with clean false-bedded sands, containing lines of small angular and subangular pebbles, mostly of quartz. The sands are covered by loess, which at the base is sandy and a little stratified, but soon graduates upwards into unstratified calcareous loess with vertical joints. It is divided into two beds by a clear line of division, the upper one of which is of a lighter colour than the lower. In another section, in a small valley to the Clay Pit The Main FIG. 2.. Maschethatte SECTION NEAR WURZBURG. 1. Alluvial plain. 2. Loess, with rubble and reconstructed loess on top. south of Marianberg, the division line is irregular, and is strongly marked by the occurrence along it of angular fragments of limestone. At Blosenberg the loess conforms to the configuration of the ground, and in all the sections I saw, the different divisions were inclined with the slope of the hill, and had not been deposited in horizontal strata that had been afterwards denuded, but rather as a mantle on the slopes of a preexisting valley. Shells of land mollusks are very abundant at Blosenberg, particularly on the slopes of the hill, where there are continuous sections by the sides of the deeply-cut paths that lead up through the vineyards. They occur here mostly in lines that give a sort of stratification to the loess. These lines of shells rise with the slope of the hill. I traced them up to a height of about 670 feet above the sea, and the loess up to 714 feet. From thence upwards the steep slope is mostly covered with limestone débris until we get to the summit, which is again covered with loess. On the northern slope of the hill I found a thin layer of characteristic loess, beneath local débris, up to a height of 880 feet above the sea. On the hill-tops it occurs to 1100 feet or more, and Dr. Sandberger informed me that it is sometimes thick on the hill-tops, and contains the characteristic loess shells, though not so abundantly as lower down in the valley. I am inclined to think that it was originally deposited continuously over the slope up to the tops of the hills, but has since been removed by denudation, as the places where it is absent are just those where it would be most likely to be washed off, and it appears to be present wherever the ground becomes flatter. In the basin of the Danube the loess is more generally and thickly spread out than even in the watershed of the Rhine. Prof. Edward Suess has kindly furnished me with much information respecting its distribution. It is found up to a height of at least 1300 feet above the sea in the upper part of the valley of the Danube. Where the river issues from the narrow gorges that it has cut through the crystalline rocks that range southwards from Bohemia, and again through the northern prolongation of the Alps above Vienna, the loess is heaped up as if deposited at the head of a lake, and just as the mud of the Rhone is now being deposited at the upper end of the Lake of Geneva. I visited Krems, where the valley-greatly contracted above where the river passes through gneiss and other crystalline rocks-widens out into a great plain, and there I found, as Prof. Suess had before informed me, the loess heaped up in a cone around the expanding mouth of the gorge. A little below the town of Krems, on the left bank of the Danube, I got the following section : FIG. 3. The Danube Ceres and SECTION NEAR KREMS. 2. Loess, with gravel and boulders at base and reconstructed loess on top. The low hills bounding the valley are all covered with loess, and sections are exposed showing a thickness of over 60 feet without its base being seen. Many bones of the mammoth have been found in it, and it is related that when in the thirty years' war the Swedes were besieging Krems they found in one of their trenches the skeleton of a monstrous animal, and that besiegers and besieged ceased from their warfare for a time to gaze on the huge teeth of the giant that had been dug up.* Some bones were shown to me at the Imperial Museum, by Prof. Fuchs, which bore cuts and indentations apparently produced by a cutting instrument, and which are supposed to have been made by man. There is no reason to question this inference, as a few palæolithic implements have also been found; and that man was a contemporary of the mammoth is now fully established. In ascending one of the many roads leading up the vinecovered slopes I found deep sections of the loess exposed, and it often rises like a wall on each side to a height of from 20 to 40 feet. The roads appear to have been purposely cut down deep, to allow not only wine-cellars but dwelling-houses to be excavated in them. The loess at Krems is compact, and almost like chalk in its homogeneous consistency, without the joints and fissures of the latter. It contains patches and seams of gravel, and pebbles of quartz are irregularly scattered throughout it. It is unstratified, but occasionally lines of division are seen separating portions of slightly dif ferent colour and composition. At its base I saw much gravel, and some boulders resting on the denuded top of stratified sands and clays. At one point I found that it had been banked up against a pre-diluvial precipice, as shown at A in Fig. 3. In some parts patches of miocene gravels lie below the stratified sands or clays, and in these the remains of Mastodon longirostris have been found. Prof. Suess informed me that he had determined that these gravels were heaped up in Miocene times in the same parts of the valley where in the Quaternary times the loess was most thickly deposited, and he thinks that at that early period the valley had assumed in a great measure its present configuration. The loess is by no means confined to the valleys of the great rivers and their tributaries. Sir Charles Lyellt and Mr. Godwin-Austent both follow the Belgian geologists in identifying it with the "Limon de Hisbaya,"which covers much * I am indebted to Prof. Edward Suess for this anecdote. † Antiquity of Man, p. 329. Quarterly Journ. Geol. Soc., vol. xxii., p, 251. of Belgium, enveloping Hainault, Brabant, and Limburg like a mantle. It extends into France, and covers the high plains between the rivers, and is most likely the same as the upland loams of the valleys of the Seine and the Somme, which occupy positions often independent of the present lines of drainage. It is even probable that it once covered the south-east of England, but has since been denuded, as Prof. Morris has shown to me some of its characteristic shells which he had gathered in patches of loess, preserved in fissures of the chalk, near Maidstone. There is also much evidence tending to prove that the loess is the equivalent in the river valleys of the northern drift that covers so much of Northern and Central Europe. Thus in ascending, from Vienna, the valley of the March, I found all the flanks of the hills covered with a loess like clay, which as I travelled northward changed to a redder colour. This clay covered the low watershed between the Danube and the Oder, to a depth of 20 feet in some places. The watershed is only about 1000 feet above the sea, and the clay covers it and follows along the flanks of the hills on either side. On the northern flanks of the range, Scandinavian blocks, that must have been carried from the far north, are found up to heights of over 1200 feet. These occur all along the northern side of the Carpathians. The diluvial clay extends much higher. According to Prof. Stur it fills the valleys on the north slope, and I have always found it extending to much higher levels than the northern blocks. This is what we might expect, for the icebergs that brought the blocks from the far north must have required a considerable depth of water to float them. In 1875, at Wolochisk, in the province of Volhynia, near the Russian frontier, whilst detained for the examination of luggage and passports, I found, in the clay that had been thrown out of a well, shells of Succinea oblonga and Pupa muscorum, two mollusks that have left their shells in the loess almost everywhere where it occurs. This was not in a valley, but on the top of the flat plateau that forms the steppes of Southern Russia. I was much impressed with the occurrence of these characteristic loess shells at this place, as no higher ground overlooks the plain, and the clay may be followed continuously for hundreds of miles, and to the north contains transported Scandinavian rocks. On my return from a visit to Southern Russia, during the present year, I determined to examine this clay, which is "the diluvium" of the Russian geologists, nearer to the mountains, and for that purpose stayed twelve hours at Podwolochisk, |