Marshall Pass is a high mountain pass at an elevation of 10,842ft (3.305m) above the sea level, located in the Rocky Mountains of central-southern Colorado, USA.
The road over the pass is gravel and sand. It may be driven by regular passenger cars in good conditions. Watch out for sudden loose-gravel breaks. And that pavement can ripple like a roller coaster track in places where “frost heaves” are caused by seasonal freezing and thawing of the ground. For the most part, Marshall Pass Road isn't too bad. There are a few rough spots, but a 2WD passenger vehicle can make it just fine if you take your time.The Marshall Pass Road is closed to wheeled vehicles during the winter months.
The unpaved sections of the road can be impassable when wet. After rain, sections of road can become decidedly hazardous when fast-flowing creek crossings and slippery mud can cause road closures. As always, check road conditions before departing. Much of the road follows a former railroad grade for the Denver & Rio Grande over 100 years ago. In the summer and late fall, this drive is especially beautiful.
More info &pics: http://ponchasprings.org/marshall-pass-road.htm