In the Truso valley — one of the longitudinal tectonic-erosional basins of the northern slope of the Caucasus — there are many accumulations of calcareous travertine deposited by springs, mostly associated with the carbonate series. One of the most important and picturesque travertine sites lies above the Kasriskhevi narrows, on the right bank of the Tergi. Here there are extensive water-sculpted travertine "fields" still actively forming. Transparent water spreads in a thin sheet over this dazzling white surface, creating countless sparkling little pools.