The Upper Tisa Valley. Preparatory proposal for Ramsay

Figure 18 Changes of the beds of River Tisa and River Szamos in the Bereg-Szatmár
Plain (after Borsy Z.)
The watercourses rise below the main ridge which serves as the watershed, and
all run toward the centre of the Carpathian Basin. All of them are received by River
Tisa. The present picture of the river system was created after the folding of the
volcanic deposit. The volcanic mound blocked the watercourses running down the
inner slopes of the sandstone deposit. Only the eroding process of the rivers of high
water output was able to keep pace with the volcanic workings. These, such as River
Tisa, River Borzhava, River Latorica and River Uzh were able to keep their valleys
open even during volcanic accumulation, and so-called volcanic gates were created
this way (Hust, Munkacheva, Uzhgorod gates). The lively force of the smaller rivers,
however, did not manage to overcome the volcanic accumulation, these rivers were
mounded behind the volcanic masses, were swollen and started searching for a course
towards the breakthroughs and gates of the bigger rivers. That is why certain rivers
developed a river system resembling a branching treetop. The most exemplary is that
of the Uzh.
The hydrography of the depressions at the foot of the mountains is chaotic and
meandering everywhere, but in this respect it is the Szatmár Plain that takes the lead.
Both River Szamos and River Tisa wanders across the plain while developing huge
bends, branching, reuniting, flowing into each other's bed. The reason for this very
indefinite flow is not only the different alluvium-carrying capacities involved in the
constructing and eroding processes, but the minor mosaic-like surface movement as
well, which has been under way up to the present day. The Tertiary surface under the
present river sediments has a very varied relief, but the transformation of the
substratum did not stop in the Pleistocene or the Holocene; on the contrary, it even
intensified.
In front of the mountains the depth of the Pannon strata ranges from 400 m to
1200 m, with depressions of NW-SE direction in them. On top of the Pannon strata
there is a sequence of Quaternary strata, which consists predominantly of large
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