According to the MTG Wiki, the Ashmouth is a demonic gateway, taking the form of a magmatic chasm (hence the card name) in the Geier Reach Mountains of the province of Stensia on the plane of Innistrad.
Now don’t get me wrong, I’m as big a fan of fiery hell-pits as the next guy (that was sarcasm; also, why do I feel the need to mention that?). But as you can also see, the mountain roads near the Ashmouth do not have proper guard rails. This makes the time-honored tradition of driving your carriage through the country-side at breakneck speeds–as one does–much more dangerous. The fellow here careening over the edge seems to have found this out the hard way. Safety regulations appear to be somewhat lax on the plane of Innistrad.