Geology Tour Road is a 17-mile loop road in Joshua Tree National Park. It consists of two parts: a 5.5-mile two-way straight section, a 6.1-mile one-way loop (clockwise), and the same 5.5-mile straight section back to the main road.
The first 5.5 miles is a sandy downhill section. There are few rocks here and it has minimal wash-boarding. The largest hazard in this section is the deep sand. 2-Wheel Drive vehicles should avoid this road due to this sand because getting stuck is super easy. AWD and 4WD vehicles should be fine for the first 5.5 miles. Any wet weather will disqualify any AWD vehicles.
The loop section is less sand and more rock. There are some deep ruts and sharp rocks, so only hi-clearance 4x4 or AWD vehicles should attempt the loop. Any wet weather will disqualify any AWD vehicles.
There is a fork in the road 2.3 miles into the loop section (southwest part of the loop) that leads down Berdoo Canyon. Berdoo Canyon is extremely difficult compared to Geology Tour Road. Only Hi-Clearance, 4x4 vehicles should attempt Berdoo Canyon. AWD vehicles, like Subaru's, or long low-clearance 4x4 SUV's, like Suburban's, should avoid Berdoo Canyon. YOU WILL GET STUCK.
There are NO WATER fill stations anywhere near Geology Tour Road, so make sure to pack extra, especially in the summer. In the Summer, a popped tire can be deadly with no water.
Along the "Tour", there are a couple dozen markers that signify different geological points of interest. Stop by the Ranger Station beforehand to get info about these different markers.