Footprints and sand ‘dunes’ in a Grand Canyon sandstone!
“There is no sight on earth which matches Grand Canyon. There are other canyons, other mountains and other rivers, but this Canyon excels all in scenic grandeur. Can any visitor, upon viewing Grand Canyon, grasp and appreciate the spectacle spread before him? The ornate sculpture work and the wealth of color are like no other landscape. They suggest an alien world. The scale is too outrageous. The sheer size and majesty engulf the intruder, surpassing his ability to take it in.”1
Anyone who has stood on the rim and looked down into Grand Canyon would readily echo these words as one’s breath is taken away with the sheer magnitude of the spectacle. The Canyon stretches for 446 km (277 miles) through northern Arizona, attains a depth of more than 1.6 km (1 mile), and ranges from 6.4 km (4 miles) to 29 km (18 miles) in width. In the walls of the Canyon can be seen flat-lying rock layers that were once sand, mud or lime. Now hardened, they look like pages of a giant book as they stretch uniformly right through the Canyon and underneath the plateau country to the north and south and deeper to the east.
The Coconino Sandstone
To begin to comprehend the awesome scale of these rock layers, we can choose any one for detailed examination. Perhaps the easiest of these rock layers to spot, since it readily catches the eye, is a thick, pale buff coloured to almost white sandstone near the top of the Canyon walls. Geologists have given the different rock layers names, and this one is called the Coconino Sandstone (see Figures 1 and 2). It is estimated to have an average thickness of 96 m (315 ft) and, with equivalent sandstones to the east, covers an area of about 519,000 sq km (200,000 sq miles).2 That is an area more than twice the size of the Australian State of Victoria, or almost twice the area of the US State of Colorado! Thus the volume of this sandstone is conservatively estimated at 41,700 cu km (10,000 cu miles). That’s a lot of sand!
What do these rock layers in Grand Canyon mean? What do they tell us about the earth’s past? For example, how did all the sand in this Coconino Sandstone layer and its equivalents get to where it is today?
To answer these questions geologists study the features within rock layers like the Coconino Sandstone, and even the sand grains themselves. An easily noticed feature of the Coconino Sandstone is the distinct cross layers of sand within it called cross beds (see Figure 3).
For many years evolutionary geologists have interpreted these cross beds by comparing them with currently forming sand deposits — the sand dunes in deserts which are dominated by sand grains made up of the mineral quartz, and which have inclined internal sand beds. Thus it has been proposed that the Coconino Sandstone accumulated over thousands and thousands of years in an immense windy desert by migrating sand dunes, the cross beds forming on the down-wind sides of the dunes as sand was deposited there.3
The Coconino Sandstone is also noted for the large number of fossilized footprints, usually in sequences called trackways. These appear to have been made by four-footed vertebrates moving across the original sand surfaces (see Figure 4). These fossil footprint trackways were compared to the tracks made by reptiles on desert sand dunes,4 so it was then assumed that these fossilized footprints in the Coconino Sandstone must have been made in dry desert sands which were then covered up by wind-blown sand, subsequent cementation forming the sandstone and fossilizing the prints.
Yet another feature that evolutionary geologists have used to argue that the Coconino Sandstone represents the remains of a long period of dry desert conditions is the sand grains themselves. Geologists have studied the sand grains from modern desert dunes and under the microscope they often show pitted or frosted surfaces. Similar grain surface textures have also been observed in sandstone layers containing very thick cross beds such as the Coconino Sandstone, so again this comparison has strengthened the belief that the Coconino Sandstone was deposited as dunes in a desert.
At first glance this interpretation would appear to be an embarrassment to Bible-believing geologists who are unanimous in their belief that it must have been Noah’s Flood that deposited the flat lying beds of what were once sand, mud and lime, but are now exposed as the rock layers in the walls of the Canyon.
Above the Coconino Sandstone is the Toroweap Formation and below is the Hermit Formation, both of which geologists agree are made up of sediments that were either deposited by and/or in water.5,6 How could there have been a period of dry desert conditions in the middle of the Flood year when ‘all the high hills under the whole heaven were covered’ (Genesis 7:19) by water?
This seeming problem has certainly not been lost on those, even from within the Christian community, opposed to Flood geologists and creationists in general. For example, Dr Davis Young, Professor of Geology at Calvin College in Grand Rapids, Michigan, in a recent book being marketed in Christian bookshops, has merely echoed the interpretations made by evolutionary geologists of the characteristics of the Coconino Sandstone, arguing against the Flood as being the agent for depositing the Coconino Sandstone. He is most definite in his consideration of the desert dune model:
‘The Coconino Sandstone contains spectacular cross bedding, vertebrate track fossils, and pitted and frosted sand grain surfaces. All these features are consistent with formation of the Coconino as desert sand dunes. The sandstone is composed almost entirely of quartz grains, and pure quartz sand does not form in floods … no flood of any size could have produced such deposits of sand …’7
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