AR 
ES Sei el nd a Zu > = 
GEOMORPHOLOGY 115 
toward the west and east by fault planes, but to the south, where 
the ground is gradually rising, it seems to thin out. The downwar- 
ping of the conglomerate here took place very probably simul- 
| taneously with the other vertical dislocations of the area. 
The conglomerate is worn away from every other part of the 
region. But how is it with the basal plane of this accumulation? 
This may still be seen in several parts, and especially, where the 
levelling process has gone through the crystalline basement. 
Already in the introduction was mentioned, that all the high 
mountains in this part of the province generally have a flat topped 
Summit, almost corresponding to the heights of the upland surface 
of the neighbouring Cordillera to the west. These summits might 
be the small remnants of a formerly levelled surface of wide exten- 
sion. It depends probably on the late age of the uplift of the pre- 
sent mountains and partly also on the greater resistence of the 
old crystalline rock-ground, that the remnants are still preserved. 
The former surface was surely worked out later than the folding of the 
continental sandstones, judging from the centre of the area, where 
_ the mentioned conglomerate does occur. This may have been deposi- 
ted on the same surface, whose remnants are preserved on the flat 
topped summits. It is evident from the character of the cong- 
lomerate, that this surface was not a „peneplain“ with a slow 
drainage. The general slope probably had quite a considerable 
gradient from a mountain region to the west, which was uplifted 
at same time as the the continental strata were folded. The great 
thickness of the conglomerate and the boulders always of old 
crystalline rocks show, that this erosion must have worked quite 
deeply into the basement ground. The detritic products of the 
continental sandstones, etc. have been carried further on and depo- 
sited on lower grounds. Some of the younger soft tertiary strata 
in the lowlands may be of that origin. 
1 Probably this phase of erosion already destroyed older peneplains and erosion 
surfaces, such as the sub-Gondwana and the subcretaceous, except in localities, 
where the overlying strata have recently been removed by erosion. 
