The mountains surrounding Muttrah and Riyaam are made of extremely tough rock withstanding weathering by the elements. It is more likely to split along jagged lines by the influence of expansion and contraction due to daily temperature variations. It was not easy to create roads in this unforgiving rock making transport over water or along the beach the preferred mode of transportation in centuries gone by. The first asphalt road in the country, between Muttrah and Muscat, started off by skirting the mountain over the beach until the village of Riyaam. and then using the natural contours of a valley between Riyaam and Muscat. At the site of this cache, along-side the original road between Muttrah and Riyaam, was a big notice board with information about the geology of the "Ophiolite" mountains surrounding these cities: a rare and fascinating type of rock closely linked to the movement of continents over the face of the Earth!
Alas the notice board has disappeared but the "lesson in geology" it contained was as follows:
The rock above you is part of one of the most significant rock outcrops in Oman. This is the internationally renowned Samail Ophiolite. The story of the ‘landing’ of the Samail Ophiolite along Oman’s northern coastline began around 90 million years ago when a several kilometer thick slab of oceanic crust started to be slowly pushed over the top of Oman’s beachfronts. The generation of this oceanic crust occurred earlier as a result of initial spreading apart of the Arabian and the Eurasian continental plates, which commenced around 270 million years ago in an ocean called Tethys lying to the north of Oman. As the plates separated, the underlying mantle melted and pools of molten rock (magma chambers) welled up to fill the gap, then hardened to form the new oceanic crust. Around 90 million years ago the continental plates started to move closer again. Normally under these circumstances the heavier oceanic crust will slide beneath the continental crust. However, in this case, the opposite occurred and for the next 20 million years rocks originating from deep within the ocean were pushed hundreds of kilometers from the deep ocean floor onto the continental plate which today carries the Sultanate of Oman. The rugged ophiolite hills around Muscat and those stretching hundreds of kilometers inland is the largest and best exposed fragment of oceanic lithosphere found on land in the world (500 km long and up to 80 km wide). The only remnant of the Tethys Ocean today is the Mediterranean Sea. The ophiolite contains many valuable minerals including copper, gold and chromites. The copper was mined from the source as early as 5,000 years ago. Oman, then known as Magan, was exporting the copper to Mesopotamia for use in the manufacturing of bronze. Today, large amounts of slag, and other evidence of early smelting processes, can still be found in numerous locations in the ophiolite region.
The cache is a small screw-top container hidden close to where this notice board once stood. It contains a log sheet and a pencil. It probably is too small to contain anything but the smallest of trackables. Please use the required amount of stealth while searching for this cache as muggles are passing by "fast and furious" along the new boulevard that has replaced the original beach road. There is one further cache in this series: Muttrah to Riyaam: Nearly there! GC4HYF0
Enjoy the hunt!