Complex sentence: In the late afternoon of August 27, the Rose-Baley Party reached the Black Mountains and made their crossing at Sitgreaves Pass, elevation 3,652 feet and named after Lieutenant Lorenzo Sitgreaves, who led an expedition party to the region in 1851.
Split into simpler sentences: In the late afternoon of August 27, the Rose-Baley Party reached the Black Mountains. They made their crossing at Sitgreaves Pass, elevation 3,652 feet and named after Lieutenant Lorenzo Sitgreaves, who led an expedition party to the region in 1851.