The Dubai Natural History Group organized a geological field trip to Wadi Naqab in the Ras Al Khaimah Emirate (RAK). Sandhya & Rohit joined them to learn about the history of the region, by analyzing rock formations which are millions of years old!
This geological field trip was led by David Kingston and the location was chosen to view the stratigraphic column in order to help understand how the rocks were originally formed. As we worked our way across the column, we saw how the rock types were influenced by the environment that prevailed at the time of deposition. We also saw evidence of how subsequent tectonic movement shaped the rocks to form the mountains we see today.
David Kingston had prepared handouts which was immensely useful for all trekkers.
There were moderate technical descriptions and discussions which were explained by David in simple terms. Fossil inspection was the fun part where a magnifying glass was most helpful.
The field trip was short in terms of distance and hardly required any climbing, though some scrambling was needed to touch the Jurassic white line, set in the Musandam Limestone.
Pangea prior to breakup, started about 175 million years ago. The Americas, Africa and Eurasia were all connected. Now the Central Atlantic Magma Platform divides the Americas from Europe in the north and Africa in the southern hemisphere. The Ethiopian fault line is another major divider. At the Wadi Naqab the rocks are layered roughly 1 million years apart each. Triassic 200-250 million years old and Jurassic 150-200 million years apart.
The Wadi Naqab stratigraphic column extended over the Triassic - Jurassic boundary. This boundary is about 200 million years old and the period prior Triassic is associated with one of the world's mass extinctions. We found evidence of this mass extinction by working our way across the stratigraphic column and looked at the fossil assemblages as they changed from one geological formation to the next. At the time of mass extinction at the end of the Triassic period – as we found out towards the end of the walk - acidification of the ocean was not the cause. We found a lot of fossils in the layer before the mass extinction occurred. As the permafrost melted, methane was released into the atmosphere then, increasing the CO2 multifold – may be the major cause for the planet being heated up and sea levels rising.
The wadi continues to be influenced by geological processes so we looked for and identified some of these recent, less dramatic processes.
Four hours flew by as David helped our understanding of visualizing millions of years in the rocks. Climbing up to the white line and touching those Jurassic era stone was a particularly fascinating experience.
Surrendering to the enormity of the timeless planet, the huge old stones and rocks, embedded with fossils, which we could actually touch and feel, time shrank.
The fault line and the up-down grazing of the stones was clearly visible. Shuba, Sumra, Sakhra are part of the Elphinstone group and are a few of the Arabic names given to the rock of yesteryears. Quarrying activity is currently going on in this area. The rounded limestones are like ball-bearings and not useful to the cement industry which needs to invest more in breaking them. So they prefer quarrying the limestone.
Small rocks indicate slow moving water in the past and large rocks indicate huge floods which could move the massive stones downhill. Brown layer is due to Silica and Iron and Grey is Limestone with impurities. The enormity of what is happening over millions of years hit me hard and filled me with hope for doing something to preserve this for posterity.
Thank you David for your patient explanations and depth of knowledge and the sharing and Sonja for organizing this special field trip.
Article by Sandhya Prakash, as seen in the DNHG Gazelle February 2018 Edition
Images by Rohit Iyengar