Wadi Mistal

July 2003, updated February 2007
 

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See also Wakan to Hadash walk

Detail map Muscat - Wadi Mistal. Distance to Hadash 155 km (one way)

A lovely bit of the Oman mountains. Wadi Mistal leads to the big Gubrah Bowl at all sides surrounded by steep walls of the Akhdar range. Easy do-able day trip from Muscat.

Google Earth Image, added February 2007 after another visit to the area. Notice the huge flat area of the Ghubrah 'bowl' that has been eroded deep into the core of the Oman mountains, surrounded by an almost continuous scarp of Permian carbonates (Saiq Formation). The outcrops in and at the lower edge of the bowl are Precambrian glacial sediments (Mistal).
Google Earth KML file of the route from Muscat to Hadash

How to get there

From Muscat follow coastal highway in northern direction to Seeb and beyond in the direction of Sohar. Take Barka roundabout, left in direction of Nakhl and follow in the direction of Rustaq. The left turnoff to Wadi Mistal is clearly signposted some 47 km from the coastal roundabout and about 15 km from Nakhl. The graded roads heads approximately south at all times. It enters the mountains through a narrow limestone gorge, winding around big boulders. Almost suddenly the scenery opens up into a wide bowl; at all sides surrounded by steep limestone cliffs. Follow the graded road always in southern direction. The village of Hadash is at the southern side of the bowl, some 32 km from the turn-off. When you approach the southern scarp you will notice small villages with green date palm groves plastered as eagles nests high on the slopes. Hadash is signposted at two junctions near the end of the road, but feel free to explore the other villages. They are all of a kind. In most cases you would need to leave your car well before entering the villages as they are originally built only for donkey access.  See also Wakan to Hadash walk

View to the south from within the Gubrah Bowl looking up to the southern scarp of the Hajar range with in the centre of the picture the village of Hijar / Wakan

Looking towards the northwest from the village of Hadash with the green datepalms with in between grapes, apricots, pomegranates and bananas growing in terraces just below the village.

The Gubrah bowl is almost like a hidden valley in the middle of the mountains, surrounded at all sides by steep limestone cliffs rising steeply to some 2000 m altitude. The low hills in the bowl all consist of very old glacial sediments, some 700-600 million years old. These have been buried deeply and were strongly deformed, giving them a sheared appearance and generally cleaving in multiple drections and therefore falling in pencil shapes. The glacial rocks look almost like sheared concrete with big boulders floating in a fine-grained background matrix, just like raisins in a cake (hence the name diamictite).

There are quite a few small villages perched high on the southern slopes, near natural springs feeding water from the think limestone packages of the Akhdar range. The trained eye quickly notices many more abandoned and ruined terraces close to the villages that are not in use anymore. In the bowl there are many grave-mounds draping the gravel terraces high above the deeply incised wadis and built of big piles of boulders. Clearly signs of more intense habitation and cultivation in the past.

The village of Hadash is at the end of the road, at an altitude of some 1500 metres, noticeable cooler compared to the bowl below . Just before the village is a vantage point offering spectacular views over the village, its terraced gardens and the Gubrah bowl in the distance below.

The spur opposite the village shows ancient ruins of what looks like another sizeable village. It is clear that the cultivated area below Hadash was once upon a time almost twice as big. The abandoned terraces are now partly used for graves. Some of the graves below the ruined village are enclosed by oval rings of stones, indicating pre-Islamic burials.

An ancient path leads up from the village (along the tower) to the scarp above, to the Saiq Plateau. It is now part of the signposted walks that have been documented by the Oman Ministry of Tourism. It is also possible to go down again to the neighbouring village of Wakan (see Wakan to Hadash Walk). There is also a direct walk along the towards the village of Wakan, starting (marked by yellow-red paint) at the back of the village.    

The village of Hadash draped against the southern flank of the Hajar range. The plantations are fed by falaj channels from natural springs in the scarp above, where porous Permian limestone overly the tight Precambrian rocks. 

Most of the rocks that crop out in the low hills within the Gubrah bowl are sediments deposited by ice some 700-600 million years ago. Big stones and fines silt/sand 'rained' from ice creating diamictites. The big stones in the fine matrix include pieces of granite that have been transported over long distance by the ice.

A big stone floating in a glacial diamictite. The comb is for size. These stones characteristically have elongated bullet shapes and this one clearly shows groves caused by other rocks scratching its sides when fixed in the moving ice.

The rocks near this location (Gubrah Formation) have been dated at around 720 My (radiometric dating).


Hadash dolomite overlying Precambrian glacial sediments. The guys on the photograph stand with their feet on glacial sediments - a cold earth-, whereas already from their knees up it would have been a normal or even warm climate with the deposition of the Hadash carbonate.

The village of Hadash, a typical Omani door

Hadash seen from the southwest, notice the terraced gardens

Hadash seen from the southeast, notice the slope at the background with Shuram (red/green) clastics overlying Khufai limestone (the ridge)

So what is special about these Precambrian glacial rocks in wadi Mistal?

The latest Precambrian or Neoproterozoic seems to have been a period in the history of the earth with widespread glaciations, even found at low latitudes and therefore possibly global. The origin of such widespread glaciations has been widely debated and gave rise to the ‘snowball earth’ hypothesis with synchronous, long-lasting (>10 million years), global glaciations, followed by a rapid warming (hothouse) and widespread carbonate deposition. The glaciations observed in rocks of the Oman mountains suggest repeated glacial cycles and the verdict is still out whether these corroborate the long lasting global glaciations of the Snowball Earth theory. Polar reconstructions for Oman indicate that Oman was at a low latitude (13° calculated for a location at Muscat, Oman) and supports extensive late Neoproterozoic cooling.  The Hadash carbonates, overlying the last glacial sediments, would represent a very rapid warming of the earth. Such overlying carbonates have been observed in similar age rocks worldwide and have been dubbed 'cap' carbonates.

The Neoproterozoic world, snowball or not, witnessed extraordinary changes from widespread glaciations reaching as far as the tropics followed by rapid warming as recorded by the paradoxical cap carbonates. Earth may have changed from icehouse to hothouse a number of times, stressing the development of early life and possibly jump-starting the evolution of life, ultimately leading to what we know as the Cambrian explosion of life on earth.

Selected geological reading

  • Hoffman, Paul.F. and Daniel P. Schrag, 2002, The snowball Earth hypothesis: testing the limits of global change. Terra Nova, 14, 129-155.
  • Le Guerroué E., P. Allen and A. Cozzi, 2005, Two distinct glacial successions in the Neoproterozoic of Oman, GeoArabia, Vol. 10, No. 2, 2005.
  • Leather, J., Phillip A. Allen, Martin D. Brasier and Andrea Cozzi, 2002. Neoproterozoic snowball Earth under scrutiny: Evidence from the Fiq glaciation of Oman. Geology, v 30; no. 10; p. 891-894.

 

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@ J. Schreurs July 2003, update February 2007