Earth’s unique topography
Our aim in this article is to look at the topography of the Earth as compared to the topography of the other bodies (planets and their moons) in the solar system. It has been expressed admirably by the evolutionist Carl Sagan—“By examining other worlds, by discovering what else is possible, by coming face to face with the alternative fates of worlds more or less like ours, we are beginning to understand better our own world”.1 It will become clear that while there are various phenomena shared between the Earth and other bodies, certain features are found only on the Earth, leading us to the conclusion that the Earth is unique geologically.
Geologists identify various processes by which the face of the Earth is being and has been shaped. These processes may be placed into five groups:
- Erosion, weathering and sedimentation.
- Impact cratering.
- Surface fracturing and distortion.
- Mountain-building, plate tectonics and continental drift.
We have arranged these processes roughly in the order of how well they are understood.
Erosional processes [group 1] are quite accurately quantised by scientists, the only unknown really being just how intense the particular activity (water for example) has been in the past.
Impact cratering [group 2] has been modelled in experiments involving detonating an explosion at ground level, so that scientists are quite confident that they know at least what energy of impact is required to produce a certain sized crater.2
Volcanism [group 3] may be observed happening in various parts of the world such as Japan and Hawaii; and surface fracturing [group 4], from seismic activity, may be observed by the unlucky inhabitants of California, Mexico, Japan and other countries. These processes are not terribly well understood, but they are certainly observed actually happening and they seem to have a purely naturalistic explanation.
At the bottom end of the scale we have plate tectonics, which is believed to be evidenced by continental drift and mountain-building by folding [group 5] (see Figure 1). These phenomena are understood only in the most general terms. Even in saying that much we are being generous. If continents are moving slowly in the directions suggested, the forces required are absolutely immense; volcanic forces being trivial by comparison. No satisfactory explanation for the source of such forces has yet been provided. But it should also be noted that scientists are far from unanimous about whether it is really happening. Actual observational evidence is highly ambiguous,3 and a growing number of scientists are rejecting the whole concept of continental drift.
To what extent are these geological processes observed on the planets and their moons? Unmanned spacecraft have been placed on the surface of Mars and Venus; while other vehicles have flown past Mercury and the moons of Jupiter and Saturn. So we now have quite a lot of information available to form an answer to this question.
Volcanism [group 3] has been identified on most of the solar system’s planets and their moons. The largest volcano known is on Mars: the 25km high Olympus Mons.4 What appear to be lava flows from volcanic outpourings are observed in many other places; notably the Moon and Mercury. Evidence strongly suggesting active volcanoes have even been found on Io, one of Jupiter’s moons.5
Impact cratering [group 2] is of course evident on the Moon and most other planets and their moons. Venus and the Earth have comparatively less impact cratering, which would be expected on account of their dense atmospheres. (It is of interest to note, however, that geologists are now recognising evidence of more impact craters on the Earth’s surface than previously.) Sometimes cratering is unevenly distributed, suggesting that later volcanic action or melting has obliterated earlier impact craters—for example, on the Saturnian moon Enceladus.6
Erosion [group 1] by both wind and water (or something like water) is evident on Mars;7 and weathering by bombardment and temperature extremes seems to be widespread.
Surface fracturing [group 4] has been observed on Mercury in the Caloris Basin.8 This is possibly due to shock from an impact, or maybe the result of solidification processes after melting. Extensive surface fracturing is also found on Mars, particularly in the Tharsis region.9 This has been correlated with stresses resulting from surface gravity and topography.
In summary then, the first four categories are widely observed. But mountain-building processes and plate tectonics [group 5] appear to be strangely absent. On Venus ‘The tectonic motion of large crustal plates appears not to have played the dominant role in altering the surface that tectonic motion has on the Earth’.10 While for Mars ‘This tectonic framework [of Earth] provides a striking contrast to that on Mars, where there are no plate tectonics’,11 and ‘Whatever the origin of Tharsis—be it deep seated uplift or long lasting volcanism—the nature of Martian tectonics is still vertical, rather than the horizontal varieties seen on Earth’.12 Indeed, the Earth differs from all the other terrestrial planets in that it alone has folded mountain chains, and platform deposits—“The Earth terrain map appears remarkably different than maps of the other terrestrial planets”.13
This conclusion, derived from comparative study of geological processes on the Earth, the other planets of the solar system and their moons, that there are some geological processes unique to the Earth, is at first startling, and then somewhat disturbing. If we have found what is possible on all the other planetary bodies, we can perhaps conclude that what is left out and therefore unique to the Earth must be due to some as yet unknown factor operative on the Earth. There is no doubt that mountain-building has taken place during the Earth’s history, but if the plate tectonics and continental drift ideas have to be rejected, then we are at a loss to know just how, that is, by what forces do mountain chains form by folding of the Earth’s crustal strata?
Surface height distribution
Given the effects of natural processes, what sort of surface height distribution would one expect for the Earth or any other planetary and lunar body? Surface fracturing and distortion might be expected to produce something like a normal distribution of heights. Volcanism, however, should give rise to a distribution with positive skew, because we would expect a small area raised up quite high, together with much filling in of depressions. Impact cratering and erosion would similarly be expected to contribute to a positive skew.
The distribution of surface heights on Venus is in fact exactly as we would expect (see Figure 2). It is not quite a normal distribution, because it is positively skewed. Furthermore, the distribution for Mars is also very close to what we would expect (see Figure 3).
The distribution for the Earth, however (see Figure 4), is entirely different from what we would expect if it was the result of the same natural processes as on all the other satellites of the solar system. Its most common surface height is 5km below sea level, which at first is rather unexpected. But then about 70% of the Earth’s surface today is covered by water-containing ocean basins. Furthermore, the surface topography height distribution is indisputably bimodal! How then could that possibly happen as a result of the natural processes common to the solar system’s members?
The waters of the deluge
In telling us about the world-changing Flood in the days of Noah, the Bible gives us much information about where the waters came from and where they went. The major source of the waters was ‘the fountains of the deep’, which are mentioned before the ‘windows of heaven’ in Genesis 7:11. These fountains were evidently created in the beginning to water the Earth (Genesis 2:5), in the centuries before there was rain. The other source of the waters was the water canopy above the firmament (atmosphere) created on the second day (Genesis 1:7). We believe that when this became unstable and fell as rain, the eyewitnesses described the event as the windows of heaven being opened.[EDITORIAL NOTE: Since this article was first published, simulations and modeling by creation scientists indicate that the water canopy idea has problems that make it is much less plausible. CMI reflects this position on the canopy hypothesis in its article Arguments we think creationists should NOT use:
This [water canopy] is not a direct teaching of Scripture, so there is no place for dogmatism. Also, no suitable model has been developed that holds sufficient water; but some creationists suggest a partial canopy may have been present. For CMI’s current opinion, see Noah’s Flood—Where did the water come from?]
So the whole Earth was covered with the flood waters, and the world that then existed was destroyed by the very waters that had been instrumental in forming it (2 Peter 3:5–6). But where did those waters go afterwards?
There are a number of Scripture passages that identify the flood waters with the present-day seas (Amos 9:6 and Job 38:8–11, note ‘waves’). If the waters are still here, how is it that the highest mountains are not still covered with water as they were in Noah’s day? Psalm 104 gives us the answer. After the waters covered the mountains (v.6), God rebuked them and they fled (v.7); the mountains rose, the valleys sank down (v.8) and God set a boundary so that they will never again cover the Earth (v.9). They are the same waters!
Isaiah gives this same statement that the waters of Noah should never again cover the Earth (Isaiah 54:9). Clearly what the Bible is telling us is that God acted to alter the Earth’s topography. New continental landmasses bearing new mountain chains of folded strata were uplifted from below the globe-encircling waters that had eroded and levelled the pre-Flood topography, while large deep ocean basins were formed to receive and accommodate the flood waters that then drained off the emerging continents. That’s why the oceans are so deep, and why there are folded mountain ranges.
If at the close of the Flood, the mountains rose while the valleys sank down, then such Earth movements must have been primarily vertical in their operation, in marked contrast to the dominantly horizontal operation of the continental drift/plate tectonics theory. What’s more, we do know of a mechanism for vertical Earth movements, one for which we have very good indirect evidence and some direct evidence.
When allowances are made for altitude and centrifugal force, the Earth appears to weigh much the same in different places. However, with the very sensitive gravity measuring instruments developed in the past few years we can weigh the Earth very accurately. Consequently we have found that the Earth’s apparent weight differs from one place to another; that is gravity is marginally different. These differences seem to be due to the different densities of the rock just below the instruments, because we know that the whole Earth can only have one weight. Therefore the differences must be caused by the different gravitational pulls of the rocks in the different parts of the crust.
For the ideal condition of gravitational equilibrium that controls the heights of continents and ocean floors, in accordance with the densities of the underlying rocks, the term isostasy (Greek for ‘in equal-standing’) was proposed by Dutton, an American geologist, in 1889.14
The idea may be grasped by thinking of a series of wooden blocks of different heights floating in water (see Figure 5). The blocks emerge from the water by amounts which are proportional to their respective heights; they are said to be in a state of hydrostatic balance. Isostasy is the corresponding state of balance between extensive blocks of the Earth’s crust which rise to different levels and appear at the surface as mountain ranges, plateaus, plains or ocean floors.
Thus the Earth’s major relief is said to be compensated by the underlying differences in rock density. Naturally, individual peaks and valleys are not separately balanced, since these minor relief features are easily maintained by the strength of the crustal rocks. None the less, the term isostasy expresses the idea that any two equal areas of the Earth’s crust, high or low, will weigh about the same. So where the crust is thin the rock material there should be more dense, and where the crust is thick, the rock material should be less dense.
These concepts have been confirmed by various evidence. For instance, gravity surveys made over the ocean gave the same result as those made on continents. The only explanation for this is to assume that according to isostasy the rocks beneath the ocean are more dense than those of the continents, because sea water is less dense than any rock. With the advent of techniques for sampling and even drilling into the rocks of the ocean floor, we have confirmed that the rocks there are denser than the average density of continental rocks.
Seismic studies, which have virtually enabled us to X-ray, as it were, the interior of the Earth, have verified that the crust is thin and dense under the oceans, whereas the continental crust is much thicker and composed of less dense rocks. And now deep crustal drilling on the continents is confirming the thickness and density of the continental crust as indicated by the indirect evidence. It would appear, therefore, that the Earth’s crust is in approximate isostatic balance.
If material were removed from the continents by erosion, then the continents would become lighter in weight and tend to rise (just as a boat rises out of the water when its cargo is unloaded). Similarly, erosion mostly carries sediments seaward, so areas of heavy sedimentation such as deltas would become heavier and tend to sink.
Such processes were quite probably operative during the Flood year. The waters covered ‘all the high hills under the whole of the heaven’, so erosion would have devastated the pre-Flood geography. The Earth’s crust was likewise broken up to release the fountains of the deep, no doubt accompanied by volcanic eruptions and the intrusion of igneous rocks. All in all, the isostatic balance of the pre-Flood crust would have been totally destroyed, so with the assuaging and retreating of the flood waters a new isostatic balance would seek to establish itself. Perhaps this is one mechanism that might account for some of the vertical Earth movements responsible for forming today’s surface topography and height distribution during the closing stages of the Flood.
Earth’s topography is absolutely unique among the explored bodies in the solar system. It has very deep ocean basins, and massive folded mountain chains stretching the length of North and South America, and across Asia into Europe. Not only are these features unique to the Earth, but no satisfactory comprehensive naturalistic explanation has yet been offered to explain their origin. The Bible indicates that God acted after the Noachic deluge to modify the topography of the Earth to accommodate the flood waters as the present seas, and the evidence bears this out.
We don’t claim to have proved the historicity of the biblical account of the Flood. But it can be seen that an understanding of this event gleaned from accepting what the Bible says explains why no satisfactory comprehensive naturalistic explanation has been found for Earth’s unique features. And it is certainly reasonable to conclude that the Earth’s unique topography is consistent with what the Bible describes.
Nevertheless many scientists will continue to search for a naturalistic explanation for mountain-building due to continental drift etc., because they deliberately reject the possibility of the Creator acting upon His creation.
References and notes
- Sagan, C., 1983. Foreword. In: Murray, B. (Ed.), The Planets, A Scientific American Book, W.H. Freeman & Co., p. vii, 1983. Return to text.
- Carr, M., The Surface of Mars, Yale University Press, pp. 39–42, 1981. Return to text.
- Snelling, A.A., What about continental drift? Have the continents really moved apart?, Creation 6(2):14–16; Wieland, C., Snelling, A.A., Has continental drift been measured?, Creation 9(3):15–18. Return to text.
- Masursky, H., Mars. In: Beatty, J.K. (ed.), The New Solar System, Cambridge University Press, pp. 86–87, 1981. Return to text.
- Johnson, T.V., 1981, The Galilean satellites. In: Beatty, J.K. (ed.), The New Solar System, Cambridge University Press, pp. 153–157. Soderblom, L.A., 1980, The Galilean moons of Jupiter. In: Murray, B. (ed.), The Planets, A Scientific American Book, W.H. Freeman & Co., pp. 74–77, 1983. Return to text.
- Soderblom, L.A., Johnson, T.V., 1982, The moons of Saturn. In: Murray, B. (ed.), The Planets, A Scientific American Book, W.H. Freeman & Co., pp. 94–95, 1983. Return to text.
- Ref. 4., pp. 88–92. Return to text.
- Murray, B., 1975, Mercury. In: Murray, B. (ed), The Planets, A Scientific American Book, W.H. Freeman & Co., pp. 10–11, 1983. Return to text.
- Ref. 2., p.117. Return to text.
- Pentengill, G.H., Campbell, D.B., and Masursky, H., 1980, The surface of Venus. In: Murray, B. (ed.), The Planets, A Scientific American Book, W.H. Freeman & Co., p. 37, 1983. Return to text.
- Ref. 2., p.113. Return to text.
- Head, J.W., Surfaces of the terrestrial planets. In: Beatty, J.K. (ed.), The New Solar System, Cambridge University Press, p. 56, 1981. Return to text.
- Ref. 12., p. 51. Return to text.
- Holmes, A., Principles of Physical Geology, Nelson, London, revised edition, p. 27, 1965. Return to text.