tracted
within a narrow gorge, which in fact cleaves asunder the Carpathian
range for a space of more than fifty miles. The limestone rock forms a
precipitous wall on either side, rising in some places to an altitude of
more than two thousand feet sheer from the water's edge. The scenery of
this wonderful pass is very varied; the bare rock with its vertical
precipice gives place to a disturbed broken mass of cliff and scaur,
flung about in every sort of fantastic form, or towering aloft like the
ruined ramparts of some Titan's castle. Over all this a luxuriant
vegetation has thrown a veil of exceeding beauty.

The fact of the Danube forcing its way through the Carpathian chain in
this remarkable manner is a very interesting problem to the geologists,
and deserves more careful investigation at their hands than perhaps it
has yet received. They seem pretty well agreed in saying that there
must have been a time when the waters were bayed back, and when the vast
Hungarian plain was an inland sea or great lake.

Professor Hull, in a recent paper on the subject,[2] states the fact of
the plains of Hungary being "overspread by sands, gravels, and a kind of
mud called _loess_, or by alluvial deposits underlaid by fresh-water
limestones, which may be considered as having been formed beneath an
inland lake, during different periods of repletion or partial
exhaustion, dating downwards from the Miocene period."

The Professor goes on to say that "at intervals along the skirts of the
Carpathians, and in more central detached situations, volcanoes seem to
have been in active operation, vomiting forth masses of trachytic and
basaltic lava, which were sometimes mingled with the deposits forming
under the waters of the lakes. The connection of these great sheets of
water with these active volcanic eruptions in Hungary has been pointed
out by the late Dr. Daubeny. The gorge of Kasan, and the ridge about 700
feet above the present surface of the stream, appear to have once barred
the passage of the river. At this time the waters must have been pent
up several hundred feet above the present surface, and thus have been
thrown back on the plains of Hungary. It was only necessary that the
barrier should be cut through in order to lay dry these plains by
draining the lakes. This was probably effected by the ordinary process
of river excavation, and partly by the formation of underground channels
scooped out amongst the limestone rocks of the