The interesting point is that these sandstone rocks extend over a tremendous area, variously estimated from 265,000 up to 660,000 square kilometres (Rahl et al. 2003. Geology 31#9 p. 761). In additional these deposits are very thick, up to 700 m (2200 ft) at Zion National Park and at lesser depths elsewhere. The total volume of these rocks is extremely large, perhaps as much as 10,000 cubic miles or 40,000 cubic kilometres. Concerning this stupendous extent of rock, some geologists call it “one of the largest sand seas known in Earth history.” (Loope and Rowe. 2003. Journal of Geology 111 p. 230).

Obviously there is nothing ordinary about the Navajo Sandstone. Naturally the first question many people ask is how this rock came to be laid down in its present location and form. The traditional explanation has always been that the diagonal layering (cross-bedding) is the result of wind action. The idea is that wind skimmed off the top of the sand dunes and deposited further dunes on top. Thus up, up, up the layers of sand were piled, with conspicuous erosion planes (flat cut-off surfaces) between the layers. This interpretation involving wind action, continues to be promoted, as in the Loope and Rowe article just cited above. Their focus is trackways and trampling on some buried rock surfaces.

The Navajo Sandstone, as a whole, has hardly any traces of plant or animal life, but there are a few sites of interest with some reptile footprints. The authors conclude that the areas with traces of life were actually wet at the time the organisms left their marks on the sand. These speculations involve an “ecological/ depositional system without modern analog” which would have developed under “unknown environmental conditions.” (p. 231) It is interesting that the authors have such difficulty explaining their observations. Perhaps there is a problem with their interpretive framework of wind deposited dunes.

The significance of the Loope and Rowe paper however pales into insignificance compared to the other article in 2003 to which we have referred. The full list of authors includes Rahl, Reiners, Campbell, Nicolescu and Allen. These scientists collected zircon crystals from two levels in the sandstone rock column, the higher of which was deposited almost 600 m (2000 ft) above the lower one. Thus these two collection sites, the one above the other, represent points near the top and bottom of the Navajo Sandstone rock layers.

These crystals, formed originally in granite rock, represent an important source of the radioactive elements uranium and thorium. Made of zirconium silicate, these hard crystals are very useful for studies involving radioactive decay. As the original granite rocks erode, many zircon and other silicate crystals end up in sedimentary deposits such as sandstone. In these sedimentary rocks, the zircon crystals, with their radioactive impurities, are useful indicators of the source rocks from which these products of erosion came. This is why these geologists set out to study zircons in the Navajo Sandstone. They wanted to know how far the sand grains had traveled to their final resting place in Utah.

To this end, the authors carried out two different analyses on the same zircon crystals. One analysis by itself might indicate a range of possible source sites, but two tests should narrow the field of possibilities. What indeed happened was that the two analyses narrowed the field to one astonishing rock source.

The analyses which were carried out included the ratio of parent radioactive uranium to stable daughter element lead, and secondly the quantity of helium left in the crystals from such radioactive decay. These tests served to rule out the nearby Rocky Mountain area as a source of the eroded crystals. Imagine the surprise of the investigators when they found that the dual signatures in their crystals suggested that the Appalachian Mountains on the northeast coast of North America, were the likely source of the sediments.

As a result of their analysis, the authors conclude that about two-thirds of the Navajo Sandstone came from the east coast, perhaps as far north as Nova Scotia in Canada and as far south as the Carolinas. Two-thirds of 40,000 cubic kilometers is 26,000 cubic kilometers of sediment. That is a lot of sand! Obviously the question arises as to how all this sediment came to the American southwest, thousands of kilometres away. In response, the authors declare that there was a sediment-dispersal system “fundamentally different from the modern one.” (p. 763) No kidding!

This scientific team suggests that there were a number of Amazon-size rivers which carried the products of erosion westward. Later, they suggest, wind moved the deposits south into their final resting site. The cross-bedding pattern in the rocks shows us that the sand was spread by an energetic process. Wind generated sand dunes however do not work as an explanation. The wind does not shear off the top part of the dune, thus depositing a new layer above the old one. (This had to happen if a cross-bedding pattern was to be produced.) Sand dunes move en masse.

Alternatively, sand waves, generated under extremely energetic water currents, do provide a reasonable explanation for our observations of cross-bedding. Studies conducted in highly energetic water currents such as San Francisco Bay, and in laboratory simulations (with flumes), indicate that sand waves can withstand horizontal sheering and deposition of another layer on top. A typical cross-bedding pattern is generated when deep sediment laden water moves, throughout its depth (not just on the surface), at 1 m or more per second.

Calculations based on laboratory-generated data suggest that a typical cross-bedded layer (about 5 m wide) in the Navajo Sandstone, was originally deposited as a 10 m high (33 ft) sandwave. The top part of the initial sandwave was then sheered away by the next, which left a similar 5 m cross-bedded layer. To drop such deposits, the water had to be about 54 m (180 ft) deep and moving at 1.5 m/second (3-5 ft/second). The inclined beds suggest that this huge body of water moved from the northeast toward the southwest. (For discussion of sandwaves, see Steven Austin. ed. 1994 Grand Canyon: Monument to Catastrophe. pp. 33-35 and Nick Eyles. 2002. Ontario Rocks: Three Billion Years of Environmental Change. pp. 50-53.)

Who needs several Amazon-size rivers when one gigantic flood is able not only to erode the sediments from the Appalachian Mountains (formed early in the flood), but also to move these sediments briskly westward and finally, to deposit them as sand waves over an extensive part of the American southwest. Such a uniform deposit had to be laid down from one huge body of water. Neither lake systems nor rivers yield so uniform a deposit.

Such current studies serve to emphasize the scale of devastation in the past. They do not paint a pretty picture of past events, but they do encourage us to reflect on the situation which lead to this terrible cataclysm. It is enough to make us count our blessings that we live now, and not then.

When we consider the other senses, we discover that taste involves four basic kinds of receptor (salt, bitter, sweet and sour) on the surface of the tongue. All taste sensations are combinations of messages from these four receptors. Colour vision similarly involves three kinds of receptor: specifically for green, red and blue light. All visual images come from messages to the brain sent from these three colour receptors as well as from a receptor for light itself. The ear, on the other hand, is said to be the most sensitive human organ. The hair cells in the inner ear are all much alike whether they are designed to detect bass tones or treble tones or anything in between. The sense of smell on the other hand, is quite a different proposition. Imagine a sense which involves 350 entirely different kinds of receptor. It is evident that smell is more interesting than we might have expected.

Biologists expect that the number of odours which an organism can detect, is proportional to the number of relevant genes. In people, about 350 different genes code for 350 different receptors. This is a very large cluster of related protein coding genes, the largest block of genes discovered so far in the human genome. This is an interesting fact when one considers all of the complicated functions of the human body. If the number of genes discovered in human DNA totals about 22,000 (as many experts now believe), then the proportion of genes coding for smell receptors is about 1.5% of that total.

The reason that we need so many receptors is because of the wide variety of chemically different odour-causing molecules in the air. The receptor molecules in the nose are located on tiny projections emerging from nerve cells. These projections are located in the mucous membranes high up in the nose. When an odour molecule collides with an appropriate receptor, the two fit together like lock and key. The receptor protein then initiates a chain of chemical reactions in the nerve cell’s membrane so that the electrical condition in the nerve cell changes. As a result, the nerve cell sends an electrical impulse toward the brain. The stimulation of various combinations of the 350 different kinds of receptor in the nose, results in the perception of at least 10,000 different odours. Each receptor responds to just one part of a molecule’s structure. Thus, if there are several reactive sites on the surface of one molecule, several different receptors may be stimulated at the same time by this one type of molecule. The blending in the brain of the different messages, leads to the sensation of a specific odour.

Some smells are mixtures of large numbers of air borne molecules. That lovely aroma of coffee, for example, contains about 500 different kinds of molecule. Although we understand these basics, the chemistry of our sense of smell is nevertheless far from clear. Some molecules with very different composition, nevertheless smell much the same. Moreover, some molecules that are extremely alike, nevertheless elicit entirely different sensations of smell. Mirror images of an organic molecule called carvone, for example, smell either like cumin or peppermint, depending upon which arrangement the component atoms assume.

A recent article in the online journal Public Library of Science Biology (May 2004) was entitled Unsolved Mystery: The Human Sense of Smell: Are We Better Than We Think? (p. 572-575). The popular perception, so author Gordon Shepherd declares, is that the human sense of smell is much less effective than that of some animals such as dogs, cats and rodents. Well maybe we should think again! Although humans have only 350 functional olfactory receptor genes, compared to much higher numbers for other mammals, it turns out that humans perform extremely well in odour detection tests. For example, when tested for the lowest amount of a chemical which they can detect, people performed better than dogs in some tests and much better than rats in others. Moreover, humans outperformed even the most sensitive machines (such as the gas chromatograph) designed to detect airborne chemicals.

Thus the author concludes, “Humans are not poor smellers… but rather are relatively good, perhaps even excellent smellers” (p. 573). The author ponders how it is that people have such excellent noses when they have so “few” detector molecules compared to various animals. The popular evolutionary interpretation is that people lost their sense of smell as they gained in brain power and the ability to walk upright. Obviously the scientists need to reconsider. We now know that people smell very well with far fewer kinds of receptor than animals require. The reason people are able to do this, apparently, lies in the much more sophisticated interpretive capability of the human brain. For any individual odour, the brain calculates how many different kinds of receptor are stimulated and what is the relative proportion of these stimulated receptors. Scientists have also recently discovered that smell perception involves many more areas of the brain than previously thought.

While humans possess fewer genes for smell, and thus fewer receptor molecules, they nevertheless smell extremely well, as well or better than animals with far more genes. It is evident that scientists who try to draw conclusions about organisms based on comparisons of their chemical components, may be in for a surprise. Dr. Shepherd therefore remarks: “The mystery being addressed here is a caution… against any belief that behavior can be related directly to genomes, proteomes, or any other type of ‘- ome’” (p. 575). (The genome is the genetic information in the DNA, and proteome is the complete list of proteins in an organism.) None of these measures adequately determines what an organism is like and what its capabilities are.

There is far more to the wonderful design of our bodies than we can even understand. Now that we realize how complicated the design of the odour detection system in our bodies really is, we will be doubly thankful for the wonderful gift of smell.

We take the motions of the planets for granted. What could be more reliable than the appearances of the planets in the night sky? The topic seems so humdrum that text books hardly discuss the solar system any more. But things are far from boring and far from being clearly understood. It was French mathematician Jules Henri Poincare (1854-1912) who first argued that the long term motions of the planets are not as predictable as had been supposed. Indeed Poincare is famous for his demonstration that there is no single and obvious solution to equations involving the motion of three or more moving objects. While it is perfectly possible to solve equations predicting the motion of two bodies about each other, once there are more moving objects, the calculations are swamped with unknowns which block clear answers. Thus n-body (where n is more than two) equations involving orbiting bodies are formally unsolvable. (This is not the case for equations in your math text books. They may seem unsolvable, but usually an answer can be found if you work long and hard enough at it!) We therefore have no theoretical explanation for planetary motions in the solar system. Why they stay in place, undisturbed by nearby moving bodies, we can’t really say.

So, one might ask, how is it that modern astronomers have computer models of planetary motion?

While the astronomers cannot make predictions of planetary motion based on theoretical considerations, they can base their models on actual past performance. Thus present-day observations are used to build models which are run backwards to see what possibly happened in the past, and forwards to see what may happen in the future. From this, astronomers draw conclusions about Mars’ past positions relative to Earth.

The scene is not simply one of the planets moving in simple orbits about the sun. German astronomer Johannes Kepler (1571-1630) first proposed that the planets follow elliptical orbits. This complicates the situation since each planet moves most rapidly when it is closest to the sun and more slowly when it is farthest from the sun. Kepler apparently was fascinated by the beautiful mathematics of the motion of the planets. In addition, he found that the length of time a planet requires to proceed once around the sun (its year), varies with that object’s distance from the sun. In other words, the distance from the sun (in astronomical units where the earth to sun distance equals one astronomical unit), once cubed, yields a value which when the square root is found, equals the number of earth years which that planet takes to orbit the sun. This may sound too much like math for your taste, but the result is that the inner planets move much faster around the sun and thus they regularly whiz past the more remote planets. The situation is like racers on a oval track. One runner may appear to be behind another, but is in reality almost a whole lap ahead.

Further complicating factors do arise however, like the shape and tilt of the elliptical orbits. While most of the planets’ orbits are nearly circular, the orbits of others are considerably longer and thinner. There is actually a fair amount of variety in orbit shape. Scientists call this value eccentricity. While the eccentricity of a circle is zero, the orbit of the planet Earth has an eccentricity of 0.017. In addition, the orbits of two planets are more nearly circular than Earth’s: namely Venus at 0.007 and Neptune at 0.010. Mars however has a considerably longer ellipse with a value of 0.093. The most extreme eccentricities are found with innermost Mercury at 0.206 and outermost Pluto at 0.248. Apparently Mercury’s elliptical orbit is particularly interesting. The ellipse rotates about the sun so that a diagram of the ellipse positions looks like daisy petals (with the sun as the daisy centre). Moreover it is Mercury and Pluto which also have the most extremely inclined (tilted) orbits while the tilt of the other orbits are all much like Earth’s.

It is the difference in orbit shape which has led to this unusual close approach of Mars to Earth. Astronomers tell us that on August 27, 2003, Mars was a mere 55 million kilometres from Earth. Depending upon the computer model used, this is said to have last happened 50,000 to 100,000 years ago. The unusual proximity came about because Mars was at its closest approach to the Earth on August 27 and also at its shortest distance from the sun on August 30. The rendezvous began on August 10, 2002.

At that time Mars was on the opposite side of the sun, about 400 million kilometres from Earth. The result of the much decreased distance in late August 2003, was that Mars appeared 85 times brighter than it did the year before. However, like ships passing in the night, the two planets are now, in their continuing ballet, moving away from each other again.

Questions arise as to why the orbits of the planets are so different. Secular explanations for the origin of the solar system would probably favour more circular orbits of similar shape for all planets. In addition, Poincare’s n-body problem suggests to mathematicians that the solar system may be chaotic. This means that the system could suddenly fall apart into random tumbling motions. Some of the computer models have suggested that if the system continued over millions of years, this would happen. In similar vein, a recent study suggests that the Earth/Moon system plays an important dynamic role in maintaining the stability of the orbits of Venus and Mercury. Without the Earth and her moon, suggests this study, gravitational push and pull from the large planets would cause the orbits of the two inner planets to immediately lose their position. (L. Innanen, S. Mikkola and P. Wiegert. 1998. Astron. J. 116: 2055). The result could potentially be a terrible crash! Our nice regular solar system would be utterly devastated. Isn’t it wonderful that the Earth and Moon are so precisely positioned?

Our image of the clockwork regularity of the solar system thus disintegrates on closer inspection. The fact that the system holds together is not automatic nor can science explain why it does so. The final lesson for us from this topic is that when things seem simple or uncomplicated, it is often merely our ignorance that makes them appear that way. What we most need to appreciate is with what finesse and how precisely our solar system is designed. The events of this past August certainly reinforce this realization.