Kremenetski hory

The Kremenets mountains are a geological accident that turned out beautiful. Where the Podolian upland ends in the north, erosion has cut its edge into a scatter of isolated, steep-sided hills that stand up out of the surrounding lowland like an archipelago run aground — and the small national park declared over them in 2009, some 6,950 hectares in the Kremenets and Shum districts of Ternopil oblast, protects the wildest of the group. Each hill is built the same way: a core of soft white Cretaceous chalk, capped and armoured by a hard shell of Sarmatian shell-limestone and cemented sand. It is the caprock that saved them from being worn flat, and the cliffs it forms — Divochi Skeli, the "Maiden's Rocks," among them — give the range its abrupt, almost alpine profile despite topping out at only 408 metres on Drabanykha.

The hills' isolation made them a refuge. On the thin, warm, calcareous soils of the summits and south slopes survives a relict steppe flora stranded here since the postglacial warm period, and one plant found on no other patch of ground on the planet: Klokov's birch, Betula klokovii, a dwarf endemic that clings to the limestone crowns of Masliatyn and Strakhova and nowhere else. The wooded flanks are oak and hornbeam giving way to beech near its eastern limit, so that a single hillside runs from shady forest at its foot to sun-scorched rock-steppe at its crest — a compression of ecosystems that is the whole point of the place. Much of this ground was already the Kremenets branch of the Medobory reserve before the park absorbed it.

Above the town of Kremenets itself rises Zamkova Hora — Castle Hill, also called Bona after Bona Sforza, the Italian-born queen of Poland who held the fortress in the sixteenth century. The stronghold on its summit was old before her time and was stormed and slighted by Cossack forces in 1648; its broken towers still crown the hill over the town's long single street. The Pochaiv Lavra, the great gold-domed Orthodox monastery that is one of the most important in Ukraine, stands only a short drive west across the same chalk country.

What's worth knowing before you go

Kremenets is the base and needs no explaining — the town wraps around the foot of Castle Hill, has bus links to Ternopil and Rivne, and puts the trailheads within walking distance. The climb to the ruined castle on Bona is the standard first outing and gives the whole archipelago of hills at a glance; the botanical crags of Strakhova and Masliatyn are for those who want the endemic birch and the steppe flowers. May and June are the flowering season and the reason to come; autumn is clear and empty on the ridges.

The detail worth carrying up the hill: the same chalk that makes these summits also seeded the region's flint industry in prehistory, and the caprock is threaded with nodules of dark flint and glassy obsidian-like inclusions — the raw material that drew people to these hills long before there was a queen or a castle.