An important chapter of the geologic history of the area was written more than 90 millions of years ago with the creation of sandstone layers on the bottom of Jurassic sea. After the sea recessed landscape enhancement processes that continue until today transformed the sandstone layer. A landscape of rock “towns”, towers, walls, gorges and ravines was born.
According to the geomorphologic classification, the southeastern part of the national park consist of the Jetřichovické stěny (“Jetřichovice rockwalls”) geomorphologic subunit – extensive significantly broken areas of rocks and forests, with practically no human settlements. From the area’s lowest point in Hřensko (116 m above sea level), a belt of mighty rock walls extends eastward. A part of it is also one of the best-known objects of the Bohemian Switzerland – the rock bridge Pravčická brána. The sandstone area is frequently enriched by individual outcrops of basalt rocks, e.g. at the hills Vosí vrch, Goliště or Suchý vrch. Outcrops of Jurassic limestone along the Lužice fault exist but are geologically rare.
The southwestern part of the national park includes the boundary areas of the Děčínské stěny (“Děčín rockwals”). Far above the deep-notched gorge of the Kamenice Stream, the highest point of both national parks raises – the hill Růžovský vrch (619 m above sea level). It is also the largest Tertiary basalt elevation of the entire Bohemian-Saxon Switzerland and is a national nature reserve that is an example of native forest ecosystems.