Complex sentence: The party climbed several mountain tops in Jotunheimen, for some of which it was the first recorded ascent, e.g. Bitihorn 1811 and Hårteigen 1812.
Split into simpler sentences: The party climbed several mountain tops in Jotunheimen. For some of which it was the first recorded ascent, e.g. Bitihorn 1811 and Hårteigen 1812.