IN THE NORTH-EASTERN CARPATHIANS. 679 



underlying rocks and external form, that where the river traverses 

 the crystalline strata above referred to, it flows along the bottom of 

 a gorge about 600 feet in depth ; but beyond this . point, towards 

 the Yisso, the soft sandstones and shales reappear accompanied by a 

 more gentle slope. 



The Yisso is one of the largest tributary streams in the upper 

 reaches of the Theiss ; and its course is one of the longest, as it takes 

 its rise about 50 miles to the south-east on the slopes of the 

 Csarkano Berg. This large affluent produces a marked deflection in 

 the trend of the main valley ; for at Rohapojana, where the two 

 streams unite, the Theiss is bent round at right angles to its former 

 course. The same effect is noticeable in the case of the Iza at 

 Szigeth ; and frequently along our route we had occasion to record 

 this feature. These lateral valleys, like the principal one, are steep 

 and narrow and thickly wooded with pine ; and, in virtue of their 

 own striking features, as well as from the influence which the 

 tributaries exercise in perpetually changing the direction of the main 

 line of drainage, they enhance considerably the effective scenery of 

 the Theiss itself. There is one important feature connected with 

 these lateral streams which must not be overlooked : it is the 

 assemblage of large " cones de dejection " immediately below their 

 confluence with the main river. These, as will be indicated presently, 

 were puzzling features at times, on account of their marked resem- 

 blance in external appearance to moraine mounds. In many cases 

 they are being broken up and subjected to reassortment, thus 

 furnishing material for the alluvial gravels of the Theiss. The 

 existence of these conical heaps, and the angular nature of the con- 

 tents, throw some light on the origin of those stretches of coarse 

 gravel which characterize the older alluvial terraces. 



Opposite the bridge which crosses the Theiss, towards the valley 

 of the Visso, an excellent section of drift is exposed on the road-side. 

 It consists of stiff brown clay, packed with stones ranging from the 

 size of one's fist to blocks several feet in diameter. These blocks 

 have the regular blunted form characteristic of ordinary Boulder- 

 clay. No scratches were detected on the smaller stones ; but in the 

 case of three large blocks we found unmistakable striae. One of 

 these blocks, weighing upwards of half a ton, was distinctly grooved 

 on three sides ; and on one side, especially, cross striae were noticeable. 

 These stones consist for the most part of a dark-blue calcareous 

 rock, probably derived from the patch of Dyas occurring higher up 

 the valley. 



From Trebousa, which is about 16 miles distant from Szigeth, to 

 Bocsko Raho, about 9 miles higher up, the Theiss flows along the 

 bottom of a deep narrow defile, closely resembling that which has 

 been already noted above Lonka. Along a great part of the way 

 the sides are almost precipitous ; but here and there the valley 

 widens somewhat, and alluvial patches of no great extent intervene. 

 These alluvial flats are hemmed in by rocky barriers, though 

 occasionally on the slopes a sprinkling of angular rubbish is 

 observable, evidently the result of the surface-wash of the hills, 



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