Complex sentence: From a small lake in the Baikal Range, in the Baikal-Lena Reserve, 10 km west of Lake Baikal, 1800m in altitude, the Lena flows north 19 km, losing 600m in altitude and becomes passable by rafts.
Split into simpler sentences: From a small lake in the Baikal Range, in the Baikal-Lena Reserve, 10 km west of Lake Baikal, 1800m in altitude. The Lena flows north 19 km, losing 600m in altitude and becomes passable by rafts.