Morfologija Haloz

Abstract

Haloze* is the name of a hilly area lying between the river Dravinja, Boč — Macelj mountain ridge and the Vinica Hills in the east.
From the geomorphological point of view there is a difference between
the western and the eastern part of Haloze. Upper Haloze (i. e. the
western part) are characterised by narrow bottoms of the valleys, by
steep slopes, by sharp ridges and finally, by considerable heights, both
relative and absolute. Older erosion levels have hardly been preserved.
In Lower Haloze, east of Rogatnica brook, the valleys are much broader
and the slopes less inclined; the ridges are smoother and the peaks are
rounded. Ali the relief is much less bold than in Upper Haloze and the
erosion levels are quite well preserved. Lower Haloze are rather a hillland, while Upper Haloze show more mountainous characteristics. In Lower Haloze the valleys are comparatively wide. The incline
of the longitudinal profiles of the brooks is small (about 3 °/oo). The
assymetric drainage pattern of the brooks is well marked in Lower
Haloze. The tributaries on the left side are longer. Eastern slopes are
therefore much steeper than the western, which are also much more
dissected by erosion. The divides are thus placed more to the west,
except in the south, where they are in a normal position. In places,
especially between Tajna and Rogatnica brooks, river capture on the
right side of the tributaries could be expected. The left tributaries of
brooks flowing towards the Drava river have cut back their courses so
much, that the divide runs on the ridges quite close to that river.
In Upper Haloze the bottoms of the valleys are narrow. The incline
of the longitudinal profile of the brooks is more than 10 %o. Drainage
pattern is more symetrical, but even here local devides tend to move
to the western side. Furthermore, it is significant that the left tributaries do not advance towards Dravinja as they do advance towards Drava in Lower Haloze.
The origin of the assymetrical hydrographic network lies in the
tilting of the whole tectonic unit in the eastern and southeastern direction. The main streams of Haloze have thus moved towards the east, whereas their left tributaries and valleys became longer and longer.
The headward erosion of the left tributaries has also contributed to
the formation of an assymetrical hydrographic network. Their local
base level has been lowered because of the downcutting along main
brooks. Further consequences of the headward erosion are also the
river captures which have probably occured. In Upper Haloze the asymetry'is less pronounced because of the greater heights. The streams cut deep valleys and the devides between them remained high and
broad. The headward erosion of the streams in Haloze is not strong. Therefore, the tributaries of Bednja on the southern side, in the area of Ravna gora, have cut their valleys far towards the north. Only in the
western parts, towards Sotla river, the divide stili runs on the line of
the mam peaks and ridges of Haloze. Small volume of the water in the
streams had also an influence on the general line of the divide. The
same is true for the character of the mountain barrier in the southern
part. The streams of Haloze flow parallel to the north and there are not
many of them. Consequently their tributaries have ample space to
develop, especially those on the left side. On the whole, the relief is
somewhat discontinuous and uneven as far as the heights are concerned. This fact is most marked in Upper Haloze.
Upper Haloze are highest in the middle, where they rise to a height
of over 500 m, in Jelovec even up to 620 m. To the south of the highest
part lies a belt of lower terrain at the height of about 400 m. In Haloze
the relative heights are quite considerale, as they reach 300 m in places
and even more. In Lower Haloze the heights are considerably lower and
they rise to over 400 m or even up to 500 m above sealevel only in the
southern belt. Whereas in Upper Haloze the highest elevations lie in
the central belt, the elevations in Lower Haloze rise steadily from the
north to the south. Relative heights in Lower Haloze are 200 to 300
metres.
A particularly important role in the evolution of the landform,
which took plače during the late pliocene period, was played by the
hydrographic network and by the composition of the rocks, which
differs. The character of the erosion levels in Haloze varies considerably.
— In Lower Haloze the rests of the older erosion levels are
comparatively well preserved. In Upper Haloze, however, they are
small and more deformed. There are no quite flat hill-top surfaces;
there is rather a series of levels of rounded peaks and short ridges. Here,
no erosion levels are widely devoloped and dominating, as it is the čase
in Lower Haloze. There, the evolution of landforms was rather different. In Lower Haloze the erosion levels have been better preserved because the downcutting and the denudation have been less strong than
in Upper Haloze where greater heights and less dense hydrographic
network have made downcutting rather than the lateral erosion more
efficient. These facts are responsible for different landforms in Upper
and in Lower Haloze, and most of ali for the character of the remnants
of the erosion levels. Six erosion levels can be discerned in Haloze. Apart from the
highest one, ali have been formed in the late pliocene period. The
highest level is at the height of 600—620 m, but it is limited to isolated spots. The most widely spread and most characteristic levels are those in the heights of 300—320 m, 340—360 m, 400—420 m and 440—460 m.
The 300—320 level is prevailing in Lower Haloze between Rogatnica
and the Plain of Varaždin. In the lower lying parts in Lower Haloze
appear only two terraces: a terrace. at the height of 260—280 m and the
pleistocene terrace along the lower courses of Rogatnica and Tajna.
This area is the first morphological unit of Haloze. The erosion level
at the height of about 360 mm represents a transitional belt between
Lower and Upper Haloze. This broad belt extends from the southern
mountain rim of Lower Haloze in the northwestern direction to Upper
Haloze. This belt can be considered as the second morphological unit
of Haloze. The prevailing erosion level in Upper Haloze is that at the
height of about 460 m. This is the elevation of the high ridges in Haloze.
The characteristic and most common level in Upper Haloze is that at
the height of 400—420 m. In two belts, one to the south and the other
to the north of even a higher part of Haloze, they encircle the 460 m
level and the other two levels appearing at the height of about 500—
540 m and 600—620 m. The latter two levels appear only in the central
part of Upper Haloze. The other high erosion levels appear, however,
also to the south of Lower Haloze. The area of the higher levels, especially in Upper Haloze, represents the third morphological unit of Haloze.