June 29th-July 5th: Antelope Valley is located within Unita Valley. The crew stays here for about a week collecting data and long/lat measurements. While there Powell and two of his crewmembers visit Unita Indian Reservation to hopefully replenish their supplies. Powell studies the tribes language and trades for some of their homemade goods. On July 5th, Frank Goodman decides he is tired of the trip and leaves the crew.

July 6th-July 10th:  As the party moves down the Green, the canyon walls begin to grow higher in elevation. The meanders in the river soon get bigger and rapids pick back up again. This part is named by the crew as Desolation Canyon due to its grand threat to the crew and their boats. On the 10th, the crew decides to rest and takes readings of the cliff walls. They determine this part of the region to be 8000ft above sea level.

July 11th-12th: As the crew tries to make their way out of the canyon, Powell’s lead boat is damaged and flipped in the river. Two ores are lost from the boat and the some instruments. The crew has to make two new ores from drift wood on the bank. The crew has one more mishap before they reach the end of the canyon.

July 13th-July 16th: The team enters a calm and smooth flowing canyon, which they named Gray Canyon, due to its gray sandstone walls. Next they pass, the mouth of the San Rafael River where they find many Indian articles. The team moves on to yet another canyon, which they named Labyrinth Canyon. The walls of the canyon continue to raise more as they pass through.

July 17th-21st: The Green River finally meets up with the Grand River, to accumulate to make the Colorado River. The crew spends the day repairing boats and takes more measurements of altitude. The team starts out on the Colorado and finds rough rapids almost immediately.

July 22nd-26th: As the team continues on, Major Powell describes the rapids in Cataract Canyon as the most difficult he has seen. The crew makes another pit stop for repairs and measurements to determine the canyon walls height above the river. Powell determined the canyon walls to be over 2000 feet above the river.

July 27th-July 31st: More rapids ahead for the team but they stumble on a herd of mountain sheep and they kill two for a feast. The team exits Cataract Canyon a couple days later. Team enters another canyon and finds Indian ruins and petroglyphs. Nearing the end of July, the team passes the mouth of the San Juan River.