This is the second in my Earth, Air, Fire and Water series, in which I will examine earth. If water is the life blood of our planet, earth is the substrate on which we live, which provides space for our homes and our agricultural activities. It is hard to separate water and earth, as they are intimately connected. While life would be impossible without water, an easy case could be made that earth is as important. Specifically soil or “dirt” is provides us with all of our agricultural vegetable, fruit and forage crops, as well as often giving us something to stand on! I have already have published a diary on agriculture (See: www.dailykos.com/...), but this is certainly a complex subject and I only commented on a small part of the issues involved.
In this diary, however, I will mostly concentrate on the earth as our home and the home of life, and earth as a substrate for everything that we do on this planet. Without a layer of humus (leaves and other organic materials), earth is made up of rock, sand, clay, and silt, as I found out very graphically when I worked as a short time (1 month) technician doing physical soil analysis under the IBP study comparing desert soils of Silver Bell, Arizona, with those of Andalgalá , Argentina. In addition, healthy soils have humus (organic matter) and various biota. Healthy soils are amazing and one could easily spend several lifetimes examining them even in a relatively small location. For one thing, because the soil and rock obscures anything under its surface (unlike water and air) and make subterranean organisms difficult, if not impossible, to observe. Some army ants, for example, are totally or nearly totally subterranean and this includes some micro ant-raiding ants in the genus Cerapachys and Neivamyrmex (See: www.antwiki.org/.... and www.antwiki.org/...) We had examples in the museum that I curated, but they were few as most of the former and at least several of the latter rarely appear above ground. In addition many burrowing or ground nest inhabitants in soil may have common to rare nest mates, which are also seldom seen. The spider Neoanagraphis chamberlini (family Liocranidae) lives in animal burrows and I usually found males in pitfall traps because they often ventured out in search of mates. One of the few spiders I collected years ago on the Camino del Diablo on the Sonora-Arizona line was this species. Many other spiders actively burrow, such as female and immature tarantulas (family Theraphosidae), trapdoor spiders (family Ctenizidae), wolf spiders (family Lycosidae), and a number of others. Larger burrowing animals include prairie dogs, gophers, moles, badgers, gopher tortoises, sand snakes, fringe-footed sand lizards, and many others.
The microorganisms of soils are legion and very poorly studied, especially in the tropics. E. O. Wilson once remarked (See: en.wikipedia.org/...) that if he could start his life over he would concentrate on microbial ecology, and I believe that soil organisms would certainly be at the front in this effort. Dry soils have less to offer than wet soils, which can harbor diatoms, various other protists, rotifers, molds, and many other creatures, but even dry soils may contain seeds, eggs of Triops and related brine shrimp and many microorganisms as spores or desiccated resting stages. We simply are not as aware of the complex biodiversity of soils as we are of the forests and deserts on and above the ground level.
Earth also, of course, contains rock and some areas are covered with a rocky surface, either as solid outcrops, lava beds, and flat bedrock, or as boulders, rocks and pebbles. Parts of deserts are often covered with “desert pavement” or surfaces of medium to small-sized rocks with a dark patina or “desert lacquer” caused by years of exposure. Volcanoes form vast areas of lava beds (igneous rocks), and these are common in the western United States. Here in the Pacific Northwest our skylines are dominated by Cascade stratovolcanoes like Mount Baker and Rainier. Many rock layers were deposited by rivers, lakes and seas as sedimentary rocks, and both main rock types can be changed by heat and pressure into metamorphic rock (See: en.wikipedia.org/....) Rocks also contain much of what civilized men and women consider valuable- gold, silver, coal, rubies, emeralds, lead, copper, aluminum, iron, oil (as oil shale), etc. In addition the earth contains liquid pools of oil and trapped natural gas.
Sand dunes fill vast areas of the world’s deserts, especially in the Sahara and Arabian deserts, but are found in all. Dust storms carry such loose soil and sand across oceans and deposit them in other continents. Sometimes these dust storms can literally turn day into night and can be seen as a wall of dust many meters high (see: www.rt.com/.... ) I have witnessed several such storms and many smaller one. I was returning from a meeting over 10 years ago and the plane could not land at El Paso Airport, because the whole city was blanked out. We had to proceed on to Phoenix and wait until the dust storm was over.
On a personal basis I am very attached to earth. The very smell of fertile soil in a forest or garden makes me very happy. Like all other jumped-up savannah apes (humans) I have to live on this planet and I derive my food and the various metals, plastics, fluids, etc. that I need or want from it. Aside from that I am emotionally connected to the wild lands and countryside. What happens to the earth affects me, my family, my friends, my neighbors, my fellow countrymen, and finally the whole planet. It is hard to be neutral on the subject. I do know that, notwithstanding my necessary scientific objectivity when I am involved in research, I find solace in the wild and am more at peace there. At night on the Camino del Diablo the silence was almost deafening and so many stars were in the sky that I had difficulty making the constellations out. The tropical night along the Trinidadian Atlantic Coast was equally awe-inspiring, although partly moonlit, with the Southern Cross and Alpha Centauri hanging above the coastal forest. I have had similar experiences in the daytime along our U.S.-Mexico border and in other places. The peace one finds in these wild places is real and abiding. The earth is a great gift and its organisms are fascinating. I, for my part, am on the side of the planet (which should be on the side of humans as well, if we were not so greedy as a species.) A tree-hugger and dirt worshiper, if you will, to my very core.
As usual, all photos are by me.
See: Water! www.dailykos.com/…
Air! www.dailykos.com/...
Fire! www.dailykos.com/...