Tusher Tunnel

Useful Information

Location: North of Moab.
(38.710678, -109.783427)
Open: no restrictions.
Fee: free.
Classification: GorgeGorge SpeleologyErosional Cave
Light: n/a
Dimension: L=25 m, H=3 m, W=2 m.
Guided tours: self guided
Photography: allowed
Accessibility: no
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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The deserts of Utah are full of extraordinary geotopes, and Tusher Tunnel is definitely one of them. It looks like a tunnel, a quite unique triangular tunnel which is absolutely straight across a hill. This mysterious place was quite impressive for visitors since centuries, and its quite easy to understand why it got such a strange name. On the other hand the geological explanation how it formed is rather obvious.

The rocks here are sedimentary rocks from the Mesozoic, mostly reddish and brownish sandstones. They are almost horizontal, but they were uplifted, and so they have a lot of thin cracks. As always, there are some layers which are harder and others which are softer, often the softer rocks are watertight, because they contain clay which makes them both soft and watertight. Other sandstones of have a lot of pores which contain water. When the weather was much rainier than today, during the last Ice Age, there was rain and rivers forming the canyons. The hard layers were more resistant against weathering and formed mesas with escarpments. As those hard rocks had cracks, a certain amount of rainwater entered the cracks, but the cracks ended on the next layer of soft rocks. The soft rocks are more flexible and did not crack so easily, and also the clay minerals in the rock tend to "heal" small cracks. So the water in the crack flew out at both ends of the crack, where the crack reaches the escarpment of the mesa.

The rocks here are not soluble, but flowing water causes erosion, mechanical abrasion of the rock and transport. The water, flowing in from the surface widened the crack, in the upper part only a little and at the bottom the amount increased. The result are a series of narrow gorges which can be very narrow in the upper part but widen at the bottom. And the water-resistant rock forms a horizontal floor.

Tusher Tunnel is the most spectacular of those gorges, the upper part is so narrow, its easily overlooked, but the lower part is a triangular passage with horizontal floor. And as the crack is straight, the tunnel is also straight. There are numerous similar cracks running parallel, some forming tunnels, others forming gorges. The Tusher Tunnel area is the place where they are most spectacular.

Like other sights in the area, the tunnel is accessible and there are even roads, parking lots and trailheads, but it is not part of a National Park, so the roads are single lane gravel roads and the parking lot a dusty lot in the desert. To reach the trailhead is possible from various directions, but high clearance and 4-wheel drive are actually required. Also, navigation is a bit tricky, as there are no signs. We suggest to use a map or a printout of google satellite data to navigate there. There are also day trips offered by operators, which include transport. Once there, it's only a 5 minutes hike to the tunnel.