Recently, the Swiss National Science Foundation has funded a project based at ETH Zurich to create digital geological maps of some areas of the Kyrgyz Tien Shan. Unfortunately, our valley lies just to the east the Kyrgyz Range project area. However, using the wider tectonic scheme and extrapolating the geology of the area that has been digitally mapped, we made a good prediction of what rocks we would find in the Shamsi Valley.
The valley is underlain by sediments of the Torsu Formation, deposited in the North Tien Shan Epicontinental Basin during the late Devonian to early Carboniferous. The Torsu Formation is divided into two parts, both of which outcrop in our valley. The early part consists of sandstones, gritstones and conglomerates, while the later part consists of reddish siltstones and sandstones.
These sediments do not form anything like the impressive granite faces to be found in nearby Ala-Archa - but that's probably why our area was previously unexplored by climbers. Instead, the area is dominated by scree slopes and loose ridges.
We found sandstones and slate as expected. The rock was loose, and formed large unstable scree slopes, but the outcrops were solid enough for careful climbing and gear placement.