The Soil Depth Dynamic

This posting will later be moved to the meteorology and biology blog, www.markmeeklife.blogspot.com .

Have you ever noticed that it never rains consistently on large areas of sand or rock, anywhere in the world? I see these as what we could call primitive landscapes which have not developed due to lack of rain.

In the posting on the meteorology and biology blog, "The Bone To Flesh Ratio", I explained my conclusion of how living things on land, with skeletons of bone, must get progressively smaller over time simply because the atoms in flesh are returned to circulation in the biosphere much faster than the atoms in bone when a creature dies. This means that, as time goes on, there must be a greater and greater amount of potential flesh available, relative to bone.

I would now like to announce a similar mechanism involving plants, and the depth of the soil in which they grow.

Plants began with those that can live on bare rock, such as mosses and lichens although they are not technically plants. The first, smallest and most primitive plants gradually break down the surface of the rock, by the intrusion of their roots, into soil so that later and bigger plants can grow into it. These, in turn, break the rock down a little bit further so that it can accommodate still larger future plants.

This process continues, the roots of the largest plants grow to fill the space available to them and then increase it a little bit further by the intrusion of their roots to break down more rock into soil. This means that the average plant, unlike the average creature with a skeleton of bone, must necessarily get larger as time goes on due to the increasing availability of deeper soil. Animals and birds spread plants around by eating the fruit with seeds, and passing the seeds through their digestive systems (for example, see "Pterosaurs And Tropical Islands", on the meteorology and biology blog). Some plant seeds are also distributed by wind.

Trees, the largest plants, were a very long time in coming. The deep soil in many places today is the result of the root action of thousands upon thousands of generations of trees, in breaking down the rock gradually with their roots.

The critical factor in the development of soil from rock is the availability of water. This determines the depth and nature of the soil in various regions. Israel, for example, is mostly dry and one of Jesus' parables involved soil that is not very deep. What about the difference between the Australian Outback and the east coast, on the other side of the Great Dividing Range? The east coast gets far more precipitation, and so the soil is much further developed because of the roots of the endless generations of plants that have flourished there.

But there is a complicating factor, the nutrients that are essential to plants can get lost when the soil gets deep. In areas of the world where glaciers reach during the ice ages, moving glacial ice acts to "plow" the soil and bring nutrients back to closer to the surface. We saw how essential this is in the posting "Glaciers And Nutrients", on the meteorology and biology blog. This development of soil in each locality is modified by the fact that glacial movement carries soil from one place to another. Britain is wet, and must have once had deeper soil, until some of it was scraped away by glaciers.

It is true that most of the structure of a plant is carbon that was pulled from carbon dioxide in the air. A leaf uses the energy of the sun to split the carbon dioxide molecule. The two oxygen atoms that were in the CO2 molecule are released back into the air and the carbon atom is retained for the plant's structure. But the soil also includes vital nutrients that were taken out, and then put back in upon death and decay, by past generations of plants.

The summary of this perspective is that the size of the average plant will gradually increase, over very long periods of time due to increasing depth of soil, and then decline due to loss of nutrients in the deep soil, in a way similar to creatures based on a skeleton of bone as described in "The Bone To Flesh Ratio". Tropical soils may have already passed the peak and entered the depletion stage, while the depletion stage is postponed in temperate areas due to the "plowing" of the soil by ice age glaciers.