Themes > Science > Life Sciences > Physical Anthropology > Evolution Should not be Taught as Fact >Fossilisation and Fossil Graveyards

Carbonization

Plants are most commonly fossilized through carbonization. In this process, the mobile oils in the plant's organic matter are leached out and the remaining matter is reduced to a carbon film. Plants have an inner structure of rigid organic walls that may be preserved in this manner, revealing the framework of the original cells. Animal soft tissue has a less rigid cellular structure and is rarely preserved through carbonization.

Petrifaction

Another common mode of preservation of plants is petrifaction, which is the crystallization of minerals inside cells. One of the best-known forms of petrifaction is silicification, a process in which silica-rich fluids enter the plant's cells and crystallize, making the cells appear to have turned to stone (petrified). Famous examples of silicification may be found in the petrified forests of the western United. Petrifaction may also occur in animals when minerals such as calcite, or silica fill the pores and cavities of fossil shells or bones.

Replacement/Sedimentation

Replacement occurs when an organism is buried in mud and its remains are replaced by sulfide (pyrite) or phosphate (apatite) minerals. This process may replace soft tissue, preserving rarely seen details of the organism's anatomy. Paleontologists have used mild acids to etch the phosphatized fossil remains of ancient fish found in Brazil to reveal structures such as gills and muscles. Although mineral replacement is rare, fossils created in this way are important in helping paleontologists compare the anatomical details of prehistoric organisms with those of living organisms.

Recrystallization

Many animal shells are composed of the mineral aragonite, a form of calcium carbonate that breaks down over millions of years to form the more stable mineral calcite. This method of preservation, called recrystallization, destroys the microscopic details of the shell but does not change the overall shape

Soft-Tissue Preservation

The soft tissues of animals are preserved only under extremely unusual conditions, and the preserved tissue usually lasts for only a short period of geological time. In the Siberian permafrost (earth that remains frozen year-round), for example, entire mammoths have been preserved in ice for thousands of years. The remains of the mammoths' last meals have sometimes been preserved in the stomachs, allowing paleontologists to study the animals' diet.

Mummification

Mummification may occur in hot, arid climates, which can dehydrate organisms before their soft tissue has decayed fully. The skin itself is preserved for only a short time, but the impressions of the skin in the surrounding sediment can be preserved much longer if the sediment turns to rock. Paleontologists have found skin impressions of dinosaurs preserved by this method.

Organic Traps

Whole organisms may become trapped and preserved in amber, natural asphalt, or peat (decaying organic matter). Amber is the fossilized remaining part of tree sap. When sap first flows from the tree, it is very thick and sticky, so as it runs down the trunk. It may trap insects, spiders, and occasionally larger animals such as lizards. These organisms can be preserved for thousands of years with details of their soft tissue, such as muscles and hair-like bristles, still intact.

Natural asphalt (also called tar) is a residue from oil that has seeped to the earth's surface from deposits in the rock below. When an asphalt pit is covered by water, thirsty animals that come to the pit to drink may become trapped in the sticky substance and be preserved. One well-known example of such an area is the La Brea Tar Pits of the Pleistocene Epoch in Los Angeles, California.

Animals may also be preserved in peat, although the acidic environment of this decaying organic matter may cause bones to lose their rigidity. Some human remains have been found in peat bogs in Denmark (2000 years old) and England (2200 years old).

Moulds and Casts

Acidic conditions may slowly dissolve away the skeleton of fossil animals preserved in rock, leaving a space where the organism used to be. The impression that is left in the rock becomes a mould. This process commonly occurs in fossil shells where the calcite shell dissolves easily. The impression of the outside of the shell is the external mould. Sometimes the inside of the shell is filled with sediment before the shell is dissolved, leaving an internal impression of the shell called an internal mould. If the space where the shell used to be is then filled with a new mineral, the replica of the shell forms a cast.

Tracks and Trails

When animals walk through soft sediment such as mud, their feet, tails, and other body parts leave impressions that may harden and become preserved. When such an impression is filled with a different sediment, the impression forms a mould and the sediment that fills the mould forms a cast. Moulds and casts of dinosaur tracks are relatively common and help paleontologists understand how these creatures moved.

False Fossils

Minerals can sometimes grow within rocks into shapes that resemble fossils. Dendrite crystals are often mistaken for fernlike fossils. Flint nodules in chalk can look like a variety of different life forms. Mineral concretions in sediments are sometimes mistaken for fossilized eggs. It is only with close study that the true nature of false fossils can be discovered.

Modern animals and plants sometimes become mummified or coated in travertine (calcium carbonate salts from springwater), or they may die while trapped in cracks in older rock strata. These remains are not true fossils, but trapped animals and plants may eventually fossilize with time.

Where Fossils Form

Fossils are found in all parts of the world, from Greenland to Antarctica. They can be found in cores drilled in and retrieved from the ocean floor, and on top of the highest mountains. Their wide geographical distribution is a result of the way the earth's surface has changed throughout its history.

Since almost every fossil used in support of evolution is found in sedimentary rock, one must question whether or not these layers were laid over hundreds of millions of years; slowly and gradually. One only has to observe the effects of minor flood-water disasters to see how quickly sedimentation layers actually build up. Considering the above factors which explain clearly the rapid conditions necessary for fossilisation in sedimentary rock, it cannot be the case that the billions of plant and animal fossils we continue to find, were fossilised over immense periods of time.

On the contrary, the huge numbers of petrified remains show quite clearly that these animals were indeed fossilised rapidly.

(Right) Fossilised tree-trunks discovered in Germany passing through several rock-strata. Example : An open-cast mine in Germany contained a large quantity of tree trunks that had been fossilised. The fossilised trunks pass through twenty feet and more, of different sedimentary rock layers. From a uniformitarian geological perspective, these trunks that have no roots and are cut clean at the bottom (using a primitive cutting tool) were fossilised in this position over hundreds and millions of years. This clearly contradicts the conditional requirements for fossilisation. These trunks would have decomposed long before those millions of years! The tree trunk, therefore, poses the most awkward problem. The sedimentary rock- strata surrounding the trunks must have been laid rapidly; more so because they are positioned upright. These tree trunks were not fossilised over hundreds of millions of years.

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