Morocco: The Trilobite’s Sahara Kingdom

In November 2019, we returned to Morocco to run our Trilobite’s Sahara Kingdom tour for the fifth time.

GeoWorld Travel’s ‘Morocco: The Trilobite’s Sahara Kingdom’ route map

Day one – arrival

The tour group gathered at our hotel in Marrakesh today. We welcomed guests from the UK, the USA and the Netherlands. We enjoyed a traditional Moroccan meal together whilst discussing the trip ahead.

Day two – Marrakesh to Ouarzazate

We started the day in the city of Marrakesh and journeyed over the High Atlas mountains to reach Ouarzazate, where we spent the night. Our first stop was near the village of Sidi Rahhal. Here we visited an agate and geoid quarry. The quarry is in latest triassic basalt that erupted in vast flood as the North Atlantic began to form, the so called CAMP event, which led to a mass extinction at the end of the Triassic. The agates have formed by water precipitating SiO 2 in vesicles (holes) left by gases that were in the magma. Agate is a cryptocrystalline form of silica which is mostly chalcedony. At our quarry, the larger vesicles also had pure quartz crystals on top of the agate with a void in the centre forming a geode.

We then crossed the Atlas mountains, seeing Triassic, Jurassic, Cambrian and Ordovician rock on our way. The Atlas Mountains are still not yet fully understood. As compression has occurred due to the collision of Africa with Europe, preexisting extensional faults (which formed with the creation of the Atlantic) have reactivated as strike-slip and thrust faults and a transpressional regime. However, the amount of uplift is much greater than expected – perhaps there is also an unknown magma source beneath?

After a picnic lunch near the summit of the pass over the Atlas, we visited a salt mine near Telouet on the old Marrakesh-Ouarzazate-Timbuktu road. In the 11th century, the salt from this mine was worth its weight in gold! This salt mine also lies on the Triassic/Jurassic boundary and has the same Triassic lavas in its vicinity as the Sidi Rahhal quarry. The salt and other evaporites formed as the new ocean basin repeatedly started to form and then dry out. Immediately above the mine were marine jurassic rocks that contain brachiopod fossils. We then drove on through Cretaceous paleogene and precambrian rocks before reaching Ouarzazate.

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Day three – Fezouata Shale Lagerstätte

Today was a fantastic day, with soft bodied anomalocarididae from the lower Ordovician Fezouata Shale Lagerstätte, giant trilobites (also from the Fezouata Shale) and ediacaran stromatolites.

The first stop, near Ouarzazate, was to see the 570-million-year-old stromatolites that grew in the Ediacaran, the last period of the precambrian. The stromatolites grew around the shore of ponds in a volcanically active area. We saw distinctive ripples in a tuff layer (volcanic ash); this tuff layer buried older stromatolites, the pond water formed the ripples, and then later stromatolites formed above the tuff layer. The stromatolites form an amazing landscape and this surface has perhaps remained unaltered for the last 570 million years!

After this, we drove on through precambrian limestone to reach Cambrian and Ordovician strata near Agdiz. Our first stop, in the lower Ordovician Fezouata Shale, was to see the discovery site of the giant Dikelokephalinid trilobites. Here we saw the diggings where fossil miners had extracted specimens and we examined their discarded fragments. We saw an articulated head and thorax of a Dikelokephalinid and one of the group also found a graptolite.

Our final stop of the day was the Lagerstätte section of the Fezouata Shale. Here, exceptional preservation has revealed soft-bodied “Burgess Shale” type fauna such as Anomalocaridids and marrellomorphs. The Lagerstätte was discovered by Mohamed Oussaid Ben Moula (known as Ben Said) during the winter of 1999-2000, and featured on the front cover of Nature in 2010. We were lucky enough to meet Ben Said and his son – one of the photos shows his son showing an anomalocaridid to our driver, Youssef.

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Day four – Alnif: trilobite capital of the world

We spent today in the Alnif area, which is nicknamed the trilobite capital of the world. In the morning we visited Jebel Tiskouine and saw trilobite diggings in the Ktaoua Formation of the upper Ordovician (Katian). The majority of the trilobites found here are the Colpocoryphe and Flexicalymene which grace fossil shops the world over, where they are often affectionately known as ‘mud bugs’. It is estimated that over 15 million of these have been extracted in the last 30 years. At the site we saw many of these trilobites. We also saw brachiopods and, in one piece of rock, there was a trilobite, gastropod, brachiopod and blastoid all together. We also saw camels with new born calves. We called into the town of Alnif for a stop and while there, we popped into a few of the many fossil shops, which sell items such as the Dicranurus monstrosus, pictured. Next we moved on to a picnic spot for lunch, before continuing on to a Cambrian site. At this site, large yellow Cambropallas are found. Our final stop of the day was at the fossil shop belonging to Ben Said, the man who discovered the Fezouata Shale Lagerstätte discoverer, that we were lucky enough to meet yesterday. Here we were able to learn more about his amazing discoveries, such as a group of giant trilobites from the Lower Ordovician, called Dikelokephalinid. After this, we returned to Alnif for a second night.

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Day five – Devonian fossils

Today was all about Devonian sites. Our first stop was on the north side of Jbel Issoumour near Bou Dib. The rock age here is late Emsian – early Eifelian. Here we saw a trilobite horizon that had been mined for several kilometres. The horizon is called the Psychopyge horizon after the spectacular Pysychopyge elegans trilobite that is found in it; many other trilobite species are found in the horizon too. Underneath this hard limestone layer are many loose fossils that are eroded out of softer marls. Fossils we were able to examine included orthocones, trilobites, blastoids, bivalves, ammonoids and algae. Once we had spent some time looking at these fossils, we then journeyed to another Emsian site where the whole desert floor was made up of fossils and loose pieces of rock. Here we were able to see brachiopods, coral, crinoids, clams, sponges and goniatites. Our lunch stop was in the village of Fezzou, where locals showed us several goniatites. After lunch, we visited a Pragian site called Atchana, where trilobites are mined from 2 trenches. These diggings yield the incredibly spinous Dicranurus monstrosus and other famous trilobites such as Scutellum, Cheirurus and Paralejurus. All of these trilobites are encased in a hard limestone and need many hours of preparation to reveal them. We then had a thrilling off-road drive across a smooth former lake bed to reach a remote desert oasis called Mharech where we spent the night at the Auberge Oasis Mharech.

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Day six – Devonian mud mounds

Our first stop of the day was either a hydrothermal mud mound or a bioherm, named Guelb el Maharch, which grew in the Givetian epoch of the Devonian and stands 45m tall. It is made of limestone lined with a crystalline calcite. This means the existing desert surface is the paleo-seafloor of that time. Crinoids and corals are very abundant here and remains of placoderm fish have also been found. Our second stop was a much larger mud mound called Mrakib. At its base is the Drotops megalomanicus trilobite horizon; this is the largest phacopid trilobite. In the diggings were some remains of these trilobites and on the desert floor there were abundant brachiopods and corals – one of our group even found a fossilised moulting phacops. We then moved to a desert area near Jbel El Krabis, where we were able to see several different species of goniatites as well as bivalves and a brittle star. At lunchtime we stopped in a hamlet and had lunch with a trilobite preparator and his family. We were able to watch his work and see some of the beautiful specimens he had prepared. Our final stop of the day was Jbel Amelane, near Rissani. Here outcrops of ‘Erfoud Stone’ could be seen. This massive Sphenoclymenia limestone contains orthoceras and the large ammonoid Gonioclymenia. This stone is used to make decorative table tops and basins in hotels. The outcrop has largely been mined away elsewhere. We finished our day in Merzouga, in the Erg Chebbi sand dunes, which will be our base for the next 3 days.

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Day seven – Dinosaurs and minerals

We spent today at the edge of the Sahara Desert in the Merzouga/Taouz area. Our first stop was in the Erg Chebbi dunes where we not only examined the dunes, but also saw fugerite, which forms when lightning hits the ground and fuses the sand into glassy tubes. After this, we moved on to the Cenomanian (100ma) Cretaceous beds of the Kem Kem. These beds have revealed over 80 vertebrate taxa including crocodiles, pterosaurs, scherorhynchid sharks, lung fish, bony fish, turtles, snakes lizards, amphibians. Perhaps most famously of all though, these beds have revealed dinosaurs The beds have a very high ratio of carnivorous dinosaurs to herbivorous dinosaurs. It is thought the shifting deltaic conditions were not good for the plants, and instead the food chain was based on the aquatic creatures. Predatory dinosaurs found in the Kem Kem include Carcharodontosaurus, Deltadromeous and, most famously, Spinosaurus. Spinosaurus teeth are abundant here.

Our next stop was the Filon 12 mine. This mine started life as a haematite mine, and is now a mine solely for mineralogical specimens. Minerals found here include vanadinite, goethite and haematite. We were taken on an underground tour by local guide Moha. After the tour we ate lunch and examined the wonderful minerals that were for sale. Our guide also showed us the jawbone of a placoderm fish he had found.

Next, we visited the Silurian (Pridoli) and we saw Scyphocrinites crinoids. These amazing crinoids were pelagic and floated under a bladder or lobolith. One of the photos shows four internal chambers in one of the loboliths, another shows the fine feeding arms of the crinoids, and another shows an assemblage of various crinoids bits. After this, we had a further two stops, firstly to see Orthoceras in a bed of earliest Devonian and secondly to see a Ludlow (mid-Silurian) bed with a mass assemblage of Orthoceras. This Orthoceras layer is quarried elsewhere to produce table tops and ornaments. All of these Orthoceras and crinoid beds were very close to each other, tilted in a syncline.

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Day eight – In and around Erfoud

Today was spent in the Erfoud area and our first stop of the day was Hamar Laghdad, also known as the Kes Kes. This is one of the best known Devonian sites in Morocco. There are 40 or more carbonate mounds in a 7km line which formed on a volcano as hydrothermal mud mounds. They have been exposed by erosion and are seen sitting on their paleosurface. Corals and trilobites used to be very abundant but have been heavily collected. We saw a rolled Phacops that was found here, as well as a bryozoan and a coral (pictured).

After the Kes Kes we visited Erfoud Quarry. The Devonian (Famennian) limestone here contains Orthoceras and the ammonoid Gonioclymenia, which is made into table tops, basins and ornaments in the Erfoud “Orthoceras factories”. The outcrop is now mostly destroyed with just blocks of stone remaining. After this stop we visited a Silurian (Pridoli) Scyphocrinites Limestone horizon. Here the crinoids are commercially mined in bellpits – one of the photos shows one for sale in an Erfoud Factory. Adjacent to the crinoid bed we saw a Silurian (Ludlow) mined bed of Orthoceras which is also turned into ornaments in the Erfoud factories.

Next we visited a nearby site on Erfoud mountain. The famous odontopleurid trilobite, Selenopeltis buchi, is mined. Echinoderms are also found at this site, including a brittlestar that we found (pictured). We had our picnic lunch at this site.

Finally we explored Erfoud city, where we visited a Orthoceras Factory and learnt how these rocks are made into furniture and ornaments. We made sure to visit the shop there too! The final destination was the Tahiri Museum. Here we saw many scientifically important specimens, as well as some lesser specimens in their shop. Pictued is a Paralejurus trilobite which has been prepared from both sides so that it resembles a piece of plastic. After this, we returned to Merzouga for a third and final night.

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Days nine & ten – the road back to Marrakesh

We spent the final full two days of the tour driving back from Merzouga to Marrakesh. We stopped at one last Devonian trilobite site before reaching Todra Gorge, where we saw impressive folding and faulting. This is caused by the collision of Africa and Europe thrusting Jurassic sediments over Eocene and Cretaceous sediments. This thrust fault forms a sudden increase in relief and is the start of the High Atlas Mountains. The gorge follows a smaller fault which is at right angles to this large thrust fault. The over-thrusted Jurassic sediments are heavily folded and, in the gorge, their bedding planes are vertical. After the gorge we had lunch in a restaurant before proceeding on to Ouarzazate where we spent the night.

The next morning we visited the World Heritage Site of Ait Ben Haddou, an impressive kasbah built in the 11th century. It has featured in several movies, such as Gladiator, Jewel of the Nile, Lawerence of Arabia and Jesus of Nazareth. We then crossed over the High Atlas pausing to examine the Tizi n’Tichka strike slip fault. Here Precambrian, Cambrian and Ordovician rocks are brought into contact with Triassic rocks. The Atlas Mountains are a transpressional regime with strike slip faults and thrusts faults. The movement is occurring on reactive NE-SW faults even thought the compressional force is N-S. We stopped at another restaurant for lunch, arriving back in Marrakesh in the mid-afternoon. The group had free-time to explore the World Heritage Site souk and before enjoying their final night in Marrkkesh.

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Day eleven – departure

After an exhilarating journey across some amazing terrain, seeing some truly magnificent palaeontological and geological sites, our group went their separate ways and returned home. We hope that they will all take away some fantastic memories form our Moroccan adventure. Huge thanks are also due to Youssef, Omar and Idir, who, once again, provided excellent driving services and local guiding.

We would also like to thank Feedspot for including us in their Top 200 Travel blogs list and their Top 30 Geology blogs list