_(From a Correspondent.)_
There is a volcanic country on the left bank between Remagen and
Andernach, highly interesting to the naturalist, but I believe not
visited by the generality of travellers. The late accounts, however, of
the formations of a similar kind in Auvergne and Clermont, in the centre
of France, and the speculations to which these phenomena have given
rise, determined me to explore this district whilst I was in the
neighbourhood. Bidding adieu, therefore, to the green little island of
Nonnenworth, I made the journey to Brohl, a convenient day's walk of
sixteen miles, passing through Oberwinter, Remagen, and Breysig, and the
other white and slated villages that enliven the river. It is here the
valley of the Rhine narrows, and the succession of ridges and dales
which the road skirts, are sometimes entirely barren, at others thickly
covered with vines and fruit-trees. Though the former plant is pleasing
in the tints of its leaf, and in the idea of cultivation and plenty that
its thick plantations present, yet there is a stiffness in the
regularity in which it grows, propped up by sticks; and it is so short,
that one's fancy as to its luxuriance, (especially if formed from such
poetry as _Childe Harold_,) is certainly disappointed. I made a
digression from the road up the little river Aar, which falls into the
Rhine near Sinzig. A more striking picture you cannot imagine. The
stream is remarkably clear and rapid, the bottom rocky, and its banks,
for a considerable distance, are literally perpendicular rocks. The Aar
is a perfect specimen of the mountain torrent; it rises in the Eiffel
mountains; and, I am told, in the winter does much mischief by
inundations. It put me in mind of the Welsh rivulets, particularly some
parts of the Dee. This _détour_ having taken up more time than I
expected, I reached Brohl, late, but in time for the supper at the
rustic Gasthoff, which, with a flask of Rhenish wine, and the company of
an agreeable German tourist who was staying there, made ample amends for
the fatigues of the day.
In setting out from Brohl by the stream of the same name, which runs
down from the Lake of Laach, where I was struck with the pieces of
pumice-stone, and the charred remains of herbs and stalks of trees
scattered over the marshes. I soon came to the valley, the sides of
which are composed of what is called, in the language of geology,
_tufa_, and in that of the country, _dukstein_, or _trass_. It is a
stone, or a hard clay, of a dull blueish colour, and when dry, it
assumes a shade of light gray. An immense quantity is quarried
throughout the valley, and is sent down the Rhine to Holland, where it
is in great request for building. The village of Nippes owes its origin
to the trade in trass, having been founded by a Dutchman, who settled
there about a century ago for the convenience of exportation. The lower
part of the mass is the hardest and most compact, and is therefore
preferred by the quarrymen; as it rises, the upper part becomes loose
and sandy, and unfit for use. You must not suppose the stream to be
clear like the Aar, for it is as thick as pea-soup, and about the same
colour, being in fact a river of trass in solution. The banks, however,
are picturesque and well wooded, particularly at Schweppenbourg, an old
castle of peculiar architecture, built on an elevated rock, and formerly
belonging to the family of Metternich, (God save the mark!) The tower is
surrounded with caverns and halls, hollowed out of the trass stone, and
profusely ornamented with fine oaks, pines, and spreading beech trees.
You may almost fancy yourself on magic ground, and looking on a fairy
castle, so peculiar is the effect. I next reached Burgbrohl and
Wassenach, passing several of the trass mills, for the stone is in many
places hard enough for mill-stones, and there is a considerable trade in
them to Holland, and thence to England and other countries. Half an hour
next brought me to the summit of the Feitsberg, one of the hills forming
the circumference of the lake; here I enjoyed a magnificent prospect on
the one side of the lake, well clothed with wood, with the old
six-towered abbey on its bank, and the heights of the Eiffel chain
enclosing it; on the other side, the view was so extensive as to give me
a glimpse of Ehrenbreitstein, and of the line of hills from thence to
the Siebengebrige. Though my object in climbing the Feitsberg was very
different, my surprise and delight in unexpectedly catching
Ehrenbreitstein at the distance of twenty-four miles even served to
withdraw my attention some time from geologizing, or from the scene
close under me. I recollect the same sensation on descrying Gravelines
sometime ago from the heights of Dover Castle, not believing the
distance to be within the powers of the telescope. True indeed is it
that
"Tis distance lends enchantment to the view.
And robes the mountain in its azure hue."
I was now in a rude and barren country, presenting a strong contrast to
the soft scenery I had left, and consisting of an elevated mountain
plateau, or table land of slate of the Greywacke sort, the heights on
the eastern side of the Rhine being of the same level, and the channel
of the river appearing as a narrow valley, which the eye overlooks
entirely. This table land is studded with isolated hills of volcanic
formation, and of a conical form, some of them having central funnels or
craters, from which the ancient eruptions have issued. The most complete
are the Hirschenberg, near Burgbrohl, the Bousenberg, between that
village and Olburg, the Poter, Pellenberg, and the Camillenberg, which
last rises about one thousand feet above the level of the surrounding
surface. There are many others extending for some distance in the Eiffel
chain and in the vicinity, but those I have mentioned are sufficient to
guide the footsteps of the inquirer. The basin of the Lake of Laach is
nearly circular and crateriform; it is a mile and a half long, and about
a mile and a quarter in breadth. Its average depth is two hundred feet,
but it is full of holes, the measure of which is very uncertain. Its
water is blueish, very cold, and of a nasty brackish taste. It has been
examined by several geologists, British and foreign, among whom is the
famous Humboldt, and there is no doubt that this great reservoir is the
crater of an extinct volcano. The fragments and minerals thrown up on
the banks are analogous to those found in other volcanic countries; and
on one side (that towards Nieder-mennig) is a regular rock of continued
lava, which is supposed to have flowed from the crater during the last
eruption. Mr. Scrope, whose opinion is entitled to great weight, thinks
it not improbable that this may have been the eruption recorded by
Tacitus, (13 lib. Annal.,) as having ravaged the country of the
Initones, near Cologne, in the reign of Nero. I should not forget to
mention that there is a cavern within the basin of the lake, the air of
which is so stifling and noxious, that animals die if forced to remain
in it, and lights are extinguished by the gas--phenomena precisely
similar to those of the well-known Grotto del Cane, near Naples.
While I am on the subject of volcanic phenomena, I may as well add a
word on the origin of the trass or tufa, which is so thickly spread over
this country. It is similar to that found near Naples, at Mont d'Or,
Carbal, and other parts of Italy; and, indeed, all the products of the
latter district are pretty nearly the same as these, allowing for the
difference of a slate surface in the one case, and a sandy and alluvial
soil in the other. The idea of the trass having any connexion with a
deluge, is, I believe, now exploded; and geologists have agreed that it
is the actual substance ejected by the volcano, subsided into a firm
paste. The rain has always been observed to fall heavily after
eruptions, and the water running down the sides of the hills, has formed
this crust, which makes the bottom and sides of the Laach. The same
causes are in action now; and if ever the lake should rise so high as to
burst its banks, it would overflow the whole country, and carry terrible
destruction with it. Such an event was actually foreseen by the
sagacious monks who formerly inhabited the abbey, for they cut a canal
nearly a mile long, to give the water vent; and the discharge by it
continues to this day. The abbey is now untenanted, and is in a
deplorable state of ruin; it was once celebrated for its hospitality and
a fine gallery of pictures; all, however, have vanished, and the ruins
are now the property of M. Delius, a magistrate of Treves. The situation
is so beautiful, surrounded as it is with fine timber, that one would
suppose it worth his while to repair the place, particularly as stone is
so plentiful in the neighbourhood. It forms, however, as it is, a
picturesque addition to the interest of the excursion to the lake, I
returned by the mineral spring of Heilbrunn, well satisfied with my
inspection of the country. The distance from Brohl to the abbey is
little more than five miles, and it is one which I would advise all
tourists on the Rhine to make if they have time, whether they be
geologists or non-geologists. I fancied I had a clearer conception of.
Aetna and Vesuvius, and the living fires, from having witnessed the
funnels of the extinct ones. At all events, though little is known as to
the causes of volcanic phenomena, enough is ascertained to convince us
that subterranean fire exists under the whole of Europe, there not being
one country or district exempt from occasional earthquakes, or some such
signs of terror.