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Creation 43(4):12–16, October 2021

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The Eye of the Sahara

Mystery circles visible from space reveal catastrophe of biblical proportions

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fig-1
Figure 1. The Eye of the Sahara, aka the Richat structure, from space. It is some 40 km in diameter and sits on a plateau 350 metres above sea level, 500 km from the Atlantic Ocean. NASA Earth Observatory.1

In the western Sahara Desert in Mauritania sits a stunning circular structure called Eye of the Sahara (figure 1).1,2 Also known as Guelb er Richât and the Richat structure, it exposes layers of sedimentary rock in concentric rings. It is about 40 km (25 miles) across, visible from space, and surrounded by desert sand (figure 2). Several different types of igneous rock (i.e. formed from the solidification of molten rock) are also exposed inside the circular structure.3 This feature speaks of continental scale catastrophe and tremendous erosion.

When it was first discovered, the Richat Structure was thought to be a meteorite impact. However, extensive field and laboratory studies in the 1960s found no evidence for high-velocity impact from space, such as shock metamorphism.

Fig_2-Richat-google-Earth-270x150km
Figure 2. The Eye of the Sahara in the western Sahara Desert is surrounded by sand. Image width is 270 km. (© Google 2020)

Now, rather than an impact from above, the structure is regarded as a huge volcanic intrusion coming from below. Magma (molten rock) pushed up into the overlying thick layers of sedimentary rock that covered the African continent at that time. This lifted and fractured the sedimentary layers and formed a volcanic dome, called a caldera. These volcanic craters form when the eruption empties the magma chamber under the volcano and the volcano collapses into itself. Something remarkable was happening to trigger this enormous volcano.

After the caldera formed, some of the top layers of the sediment were eroded off. This left the circular section of the dome visible on the surface. The different layers of sediment were of different hardness and formed circular ridges and valleys.

In 2014, geologists Guillaume Matton and Michel Jébrak from the University of Quebec, Montreal, Canada, reported data they had gathered from three visits to the Richat structure.4 They also described a scenario for how the structure formed. From their proposal we can see how their findings are nicely explained by the processes that occurred during Noah’s Flood.

The beginning of the formation

 Fig_3-Richat-sequence-2
Figure 3. Hypothetical sequence for forming the Richat structure. The geological section runs from the south-west to north-east. Width of section is some 50 km. The vertical scale is exaggerated 35 times. See text for discussion. From ref. 4 (A) First stage. Initial magma emplacement and uplift of caldera roof. (B) Second stage. Magma emplacement continues. (C) Third stage. Magma emplacement completed. Caldera roof collapsed. (D) Fourth and final stage. From emplacement to the present. 100 metres of surface erosion.

Figure 3A shows Matton and Jébrak’s first stage of the formation of the Richat structure.5 It is a geological section from the south-west to the north-east extending some 50 km across the structure. Note how the vertical scale changes: 0 to 200 m at the top and 3km at the bottom. Keep in mind that this diagram is an interpretation of the below-ground geological structure (based on what has been observed on the surface). Also, it is at a time in the past, so it was not observed and involves speculation.

Note that layers of sediment extend across the top of the figure. These consist of quartz sandstone, limestone, and other sediments (such as siltstone and mudstone). The legend for the diagram is at the bottom of the figure. Note that the layers are constant in thickness across the figure, indicating that the layers extend far beyond the edge of the figure.

These layers are part of a large sedimentary deposit in what has been called the Taoudenni Basin (figure 4), which extends some 600 km from west to east, and 2500 km north–south. The ages assigned to these uppermost sediments of this basin are Late Ordovician (450 million evolutionary ‘years’) to Carboniferous (300 million evolutionary ‘years’).6 By locating these sediments on the geology transformation tool (figure 5), we can see that the sediments were deposited as the waters of Noah’s Flood were rising. There was still some time before the waters of the Flood would peak at around the Cretaceous.

Sediments that extend over a large geographical extent like this are a characteristic of deposition as the floodwaters were rising. The reason for the huge geographical area is that the Flood involved catastrophic processes of high energy and of continental scale. (See Sedimentary blankets: visual evidence for vast continental flooding.)

Note that in figure 3A the mafic magma (black and rich in iron and magnesium) is just beginning to push up from below and has fractured the layers of sediment in several places. The magma is also squeezing up through a few vertical cracks, erupting above the ground, throwing ash and dust into the air, and depositing lava on the surface. The diagram indicates that the force of the magma has pushed up the rocks across the crater (i.e. a ‘lid’ 40 km across and 400 m thick) some 100 metres.

Timing of the intrusion and its cause

 fig-4
Figure 4. The Richat structure formed in sediments deposited in the Taoudenni Basin, which extends some 600 km from west to east, and 2,500 km north–south.

Matton and Jébrak say this volcanic intrusion began shortly before 100 million evolutionary ‘years’ ago.7 We recall that this is when the global super-continent Pangea started to break up, and the continents began to move toward their present locations. From the geology transformation tool (figure 5) we see that 100 million years is around the middle of the Cretaceous. Further, this is around the time when the waters of Noah’s Flood were reaching their peak and about to begin receding from the earth. Previously, I have tied this break-up of Pangea to the opening of the ocean basins allowing them to receive the waters of Noah’s Flood (See: Recessive Stage of Flood began in the mid-Cretaceous and eroded kilometres of sediment from continent and Geologists see effects of Noah’s Flood in Africa).

Connecting the timing of this intrusion to the sinking of the ocean basins and the break-up of Pangea helps identify the cause of the intrusion. Such significant movement of the earth’s crust on a global scale over a month or two would melt rock and produce magma. Down-drop of the oceans and uplift of the continents would stress the edges of the continents, fracturing the crust and squeezing molten magma up through fractures in the continental crust.

Matton and Jébrak identify the source of the initial mafic magma as the sub-continental lithospheric mantle (i.e. the earth’s mantle just beneath the continental crust).8 This is deep under the continent, and is evidence that the lowering of the ocean basins and the uplift of the continents during Noah’s Flood involved rapid, large-scale crustal movements that impacted deep into the earth. This is evidence supporting the global, catastrophic nature of Noah’s Flood.

Emplacement of the rest of the intrusion

 Fig_5-Geology-transformation
Figure 5. Geological transformation tool. The left side of the figure shows the geologic column with its labelled subdivisions. The evolutionary times assigned are shown in the middle. To the right of the figure coloured arrows provide a reinterpretation into a biblical geologic history. For more information see The geology transformation tool.

Matton and Jébrak’s second and third stage diagrams (figures 3B and C) show how they envisage the structure continued to form.5 First, the composition of the magma at the bottom changed from basaltic (black, rich in iron and magnesium) to rhyolitic (pale, rich in silica and aluminum). This indicates the magma source changed from the mantle to the crust. (Likely the heat of the basaltic magma melted the crustal rocks as it rose through the crust). Second, a small pile of breccia formed at the top. Third, volcanic eruptions continued but eventually stopped. Fourth, the huge ‘lid’ of the crater (40 km across and 400 m thick) dropped down, different pieces dropping by different amounts.

In geological terms, Matton and Jébrak envisage these processes happened relatively quickly. They say it began “shortly before 100 Ma” and finished “shortly after.”7 In real time during Noah’s Flood this would have only taken days or weeks.

The diagrams (figures 3B, C, and D) also show volcanic eruptions composed of carbonatite (C) and kimberlite (K). Carbonatite igneous rock consists of over 50% carbonate (limestone) minerals, in contrast to basalt and rhyolite. However, of more relevance to geological catastrophe is the Kimberlite magma (K), because this rock formed deep within the mantle at depths between 150 and 450 kilometres. It erupts rapidly and violently. Such rapid and violent eruption from such depth within the earth indicates the enormous scale of the catastrophe that formed the Richat structure, which is consistent with the biblical Flood.

After the eruption

In figure 3D Matton and Jébrak show what they envisage happened from the time the eruption finished until the present day.5 The only thing they changed from figure 3C is to remove about 100 metres of sediment from the surface, which they assume was removed by normal erosion, i.e. by slow-and-gradual weathering. The softer sediments eroded more than the hard sediments. Consequently, the hard sediments are now more prominent, forming the circular quartzite ridges.

Just 100 metres of erosion from the surface seems far too little. The top sediments are said to be Carboniferous (300 million evolutionary ‘years’) but the intrusion did not occur until the mid-Cretaceous (100 million evolutionary ‘years’). That is 200 million years of sedimentation. In the evolutionary view that would have added kilometres of sediment onto the continent before the intrusion. From the catastrophic biblical perspective the amount of deposition would be the same. However, that thickness of sediment is not shown on the first three diagrams (figures 3A, B, and C). It would have been there, and the material would have been eroded away during the Recessive stage of the Flood.

On this issue, geologists McCarthy and Rubidge describe sedimentation in Southern Africa during the break-up of Gondwana (the southern portion of Pangea). They say:

“Unlike the Karoo—where sedimentation occurred for nearly 120 million years, much of it on land, producing a complete record of terrestrial life during the Permian, Triassic and early Jurassic Periods—the later Jurassic and Cretaceous Periods during which the break-up of Gondwana occurred are poorly documented in the rocks of South Africa. During this time it seems that southern Africa was elevated and the interior was experiencing erosion. Sedimentation deposition was taking place mainly in the developing Indian and Atlantic oceans, now all off-shore areas.”9

Although the Richat structure is not in Southern Africa, we would expect that a similar depth of sediment would have been deposited over the area and subsequently eroded away. That is also what other continents have experienced. We would expect north-west Africa to have the same experience.

Perspective interpretation

Fig_6-Perspective_diagram
Figure 6. A perspective west-east view of the Richat complex (looking north) showing the possible shape of the magmatic chamber. The width of the section is 60 km. The vertical exaggeration is about 35 times. From ref. 4

Figure 6 shows Matton and Jébrak’s interpretation of the Richat complex indicating the possible size and shape of the magma chamber.7 The width of the section is 60 km and runs from west (left side) to east (right side). The vertical exaggeration is 35 times. The sedimentary strata, which run across the figure above the magma chamber, maintain an even thickness, indicating that they extend much further than shown on the figure. (The geographical extent of the sedimentary Taoudenni Basin is shown in figure 4). Notice that the strata to the east (right side) of the figure dip down slightly to the east. The strata to the west (left side) dip down to the west. (The vertical exaggeration of the figure makes these dips look much more than they are in real life.) The hinge point is aligned north–south (out of the figure) and runs through the magma chamber. This bending of the strata is consistent with the Atlantic Ocean to the west sinking and the African continent lifting about mid-way through Noah’s Flood. The stress this tectonic movement placed on the edge of the African continent generated the magma below the crust and thrust it up through the crust, forming the volcanic intrusion that is now the Eye of the Sahara.

Summary and conclusions

The Eye of the Sahara is the surface expression of a subsurface volcanic intrusion that created a volcanic crater—a caldera. The intrusion pushed into sedimentary rocks that were deposited as the waters of Noah’s Flood were rising, some 4,500 years ago. The intrusion occurred just before the waters reached their peak and began to recede off the African continent into the ocean.

The intrusion was caused by stresses produced in the earth’s crust as the continent began to uplift and the ocean basins began to down-drop. These crustal movements were of such magnitude that they impacted deep into the earth producing magma and pushing it up through the crust. After emplacement, the sediments above the Richat structure were eroded by the waters of Noah’s Flood. The waters did this while they covered the continent and then as they flowed into the ocean. It is likely that kilometres of thickness of sediment covered the area when the eruption occurred, much more than what covers the area at present.

The Eye of the Sahara is a testament to the catastrophic events and processes of Noah’s Flood, recorded in the Bible.

Posted on homepage: 12 November 2020

References and notes

  1. Geology Science, Eye of the Sahara or Richat Structure, 2020; geologyscience.com/gallery/eye-of-the-sahara-or-richat-structure, Return to text.
  2. Richat Structure (photographed December 17, 2011), NASA Earth Observatory, Image of the Day, April 29, 2018; earthobservatory.nasa.gov/images/92071/richat-structure Return to text.
  3. This includes stunning pale rhyolites, a central pile of large, kilometre-sized angular chunks of rock (mega-breccia) altered by hot, underground fluids, and dark gabbro. Return to text.
  4. Matton, G. and Jébrak, M., The “eye of Africa” (Richat dome, Mauritania): An isolated Cretaceous alkaline–hydrothermal complex, Journal of African Earth Sciences 97: 109–124, 2014. Return to text.
  5. Matton and Jébrak, ref. 4, p.121. Return to text.
  6. Matton and Jébrak, ref. 4, p.110. Return to text.
  7. Matton and Jébrak, ref. 4, p.122. Return to text.
  8. Matton and Jébrak, ref. 4, p.123. Return to text.
  9. McCarthy, T. and Rubidge, B., The Story of Earth and Life: A Southern African Perspective, Struik Nature, Cape Town, p. 249, 2005. Return to text.

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