At the time that Darwin’s On the Origin of Species was published, the earth was “scientifically” determined to be million years old. By , it was found to be 1. In , science firmly established that the earth was 3. Finally in , it was discovered that the earth is “really” 4. In these early studies the order of sedimentary rocks and structures were used to date geologic time periods and events in a relative way. At first, the use of “key” diagnostic fossils was used to compare different areas of the geologic column. Although there were attempts to make relative age estimates, no direct dating method was available until the twentieth century. However, before this time some very popular indirect methods were available. For example, Lord Kelvin had estimated the ages of both the Earth and the Sun based on cooling rates. The answer of 25 million years deduced by Kelvin was not received favorably by geologists.
Sand Sand isn’t a boring material if you know what you are looking at! Highly rounded sand grains from the Gobi Desert of Mongolia. Wind-blown sand sustains repeated tiny impacts as it bounces along Earth’s surface. These impacts gradually abrade sharp protrusions from the grains and give their surface a “frosted” luster. The width of this view is approximately 10 millimeters. The white grains are coral fragments, and the gray-black grains are pieces of basalt.
The fossil record leaves an inescapable impression on the honest observer. It certainly doesn’t communicate the macroevolutionary picture. The record of the past written in stone contains no evidence that any particular animal ever morphed into a fundamentally different type of animal.
The Radiometric Dating Game Radiometric dating methods estimate the age of rocks using calculations based on the decay rates of radioactive elements such as uranium, strontium, and potassium. On the surface, radiometric dating methods appear to give powerful support to the statement that life has existed on the earth for hundreds of millions, even billions, of years. We are told that these methods are accurate to a few percent, and that there are many different methods.
We are told that of all the radiometric dates that are measured, only a few percent are anomalous. This gives us the impression that all but a small percentage of the dates computed by radiometric methods agree with the assumed ages of the rocks in which they are found, and that all of these various methods almost always give ages that agree with each other to within a few percentage points. Since there doesn’t seem to be any systematic error that could cause so many methods to agree with each other so often, it seems that there is no other rational conclusion than to accept these dates as accurate.
Dinosaurs’ Living Descendants
What about the fact that the “simple” organisms are buried in the lower levels and the more “complicated” ones are buried in the higher levels? Doesn’t this fact support the notion that simple organisms evolved into more and more complex organisms over time, with the more complex organisms buried and fossilized above the earlier and simpler life forms? Certainly this seems like a very logical assumption. But, things just aren’t that easy.
A fossil (from Classical Latin fossilis; literally, “obtained by digging”) is any preserved remains, impression, or trace of any once-living thing from a past geological es include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood, oil, coal, and DNA remnants. The totality of fossils is known as the fossil record.
Renaissance Now, let’s look at some specific examples. One type of atom that does not normally react is Neon. See the picture to the left. It already has the correct number of electrons in it’s outside electron layer so Neon does not react. Neon, along with Helium and Argon are known as non-reacting gasses because they do not need to react to be stable.
Other types of atoms such as Hydrogen, Carbon, and Oxygen do not have the correct number of electrons to be stable by itself.
A phenotypic characteristic, acquired during growth and development, that is not genetically based and therefore cannot be passed on to the next generation for example, the large muscles of a weightlifter. Any heritable characteristic of an organism that improves its ability to survive and reproduce in its environment. Also used to describe the process of genetic change within a population, as influenced by natural selection.
Figure 2. How relative dating of events and radiometric (numeric) dates are combined to produce a calibrated geological time scale. In this example, the data demonstrates that “fossil B time” was somewhere between and million years ago, and that “fossil A .
Paleontology is the study of fossils. A fossil is defined as any trace of a past life form. Thus, although wood, bones, and shells are the most common fossils, under certain conditions soft tissues, tracks and trails, and even coprolites fossil feces may be preserved as fossils. Although most of the fossils that paleontologists study are several thousands to several billions of years old, there is no absolute minimum age for a biological structure to be a fossil.
Paleontologists study fossils and attempt to use them to reconstruct the history of the Earth and the life on it. Some paleontologists study the ecology of the past; others work on the evolution of fossil taxa. For additional information on the subdisciplines of paleontology, read our “What is paleontology? How does paleontology differ from anthropology and archaeology?
Some paleontologists do study the fossil record of humans and their relatives. However, paleontology as a whole encompasses all life, from bacteria to whales. Paleontology does not usually deal with artifacts made by humans. However, archaeologists and paleontologists might work together. For instance, a paleontologist might identify fossil animal bones or plant pollen associated with an archaeological site, to find out what the people who lived there ate; or a paleontologist might be called on to analyze the climate at the time a particular archaeological site was inhabited.
Index to Creationist Claims
These formations may have resulted from carcass burial in an anoxic environment with minimal bacteria, thus slowing decomposition. Stromatolites Lower Proterozoic stromatolites from Bolivia , South America Stromatolites are layered accretionary structures formed in shallow water by the trapping, binding and cementation of sedimentary grains by biofilms of microorganisms , especially cyanobacteria. While older, Archean fossil remains are presumed to be colonies of cyanobacteria , younger that is, Proterozoic fossils may be primordial forms of the eukaryote chlorophytes that is, green algae.
One genus of stromatolite very common in the geologic record is Collenia. The earliest stromatolite of confirmed microbial origin dates to 2.
The standard approach to looking at fossils in the geological column is to assume that lower is older. Since the geologic column represents millions of years of Earth’s history, then obviously the fossils in each of the layers must be the same age as the layer in which they are found. What is especially interesting is that the fossils do appear to show a progression from the most “simple” of.
Fossils of hard mineral parts like bones and teeth were formed as follows: Some animals were quickly buried after their death by sinking in mud, being buried in a sand storm, etc. Over time, more and more sediment covered the remains. The parts of the animals that didn’t rot usually the harder parts likes bones and teeth were encased in the newly-formed sediment. In the right circumstances no scavengers, quick burial, not much weathering , parts of the animal turned into fossils over time.
After a long time, the chemicals in the buried animals’ bodies underwent a series of changes.
The shells are found as fossils in Maryland and Virginia. Ecphora was one of the first fossils from the New World to be illustrated in a scientific work in Europe. Massachusetts State Fossil Age: The dinosaur tracks in the Connecticut Valley date from about million to million years ago.
An exceptionally high density of giant handaxes dated to ,, years ago has been uncovered at an archaeological site in Galicia, northwest Spain.
Exceptional preservation How fossils are formed Fossilisation only happens in the rarest of cases, when a plant or animal dies in the right circumstances. Animal corpses are usually eaten by something, or bacteria rots them away before fossilisation can occur, and even hard parts like bones and shells are eventually destroyed through erosion and corrosion. The trick to becoming a fossil is to die in a location where your body – or bits of it – are protected from scavengers and the elements.
This means getting buried in sand, soil or mud and the best place for that is on the seabed or a river bed. Only in very rare cases do the soft parts of animals – the flesh, skin and internal organs – become fossils. Even when buried under mud or soil, decay still takes place, though lack of oxygen does slow it down.
If a skeleton is dug up at this stage, it will still be made of bone. Remains like these that haven’t truly fossilised yet are sometimes called ‘sub-fossils’. As more time passes, sub-fossils become buried deeper and deeper. What was mud or sand becomes compressed on its way to becoming rock. But even safely sealed away underground, time doesn’t stand still. Chemicals and minerals percolate through the sediment and the original bone or shell gradually recrystallizes.
Are Fossils the Result of Noah’s Flood?
Acknowledgements Introduction his document discusses the way radiometric dating and stratigraphic principles are used to establish the conventional geological time scale. It is not about the theory behind radiometric dating methods, it is about their application, and it therefore assumes the reader has some familiarity with the technique already refer to “Other Sources” for more information. As an example of how they are used, radiometric dates from geologically simple, fossiliferous Cretaceous rocks in western North America are compared to the geological time scale.
To get to that point, there is also a historical discussion and description of non-radiometric dating methods.
How radiometric dating works in general: Radioactive elements decay gradually into other elements. The original element is called the parent, and the result of the decay process is .
A new study, published in the journal Nature on September 24, , finds that these fossils are either algae or early animal embryos, but are not bacteria or single-celled protists. This specimen is a mere 0. Lei Chen and Shuhai Xiao A multicellular specimen of the Megasphaera fossils shows dividing cells in its interior. The peripheral cells on the outside of the cell are slightly elongated, suggesting cell differentiation. Differentiated cells are a trademark of complex life.
Animals, for example, have hundreds of types of cells that perform specific roles: Geobiologist Shuhai Xiao of Virginia Tech and his colleagues suspect that these fossils might represent a transition from simple single-celled life to more complex multicellularity in the world’s oceans million years ago. Lei Chen and Shuhai Xiao Among the possibly differentiated cells of the Megasphaera fossils are unusual structures dubbed “matryoshkas” by the study researchers.
Matryoshka is the Russian word for nesting doll. The cells in these matryoshka cluster are smaller than the cells in the rest of the fossil and appear to have been fossilized in the midst of dividing and growing. Xiao and his colleagues believe that these matryoshkas may be clusters of reproductive cells, segregated from the somatic, or body, cells of the organism.
Lei Chen and Shuhai Xiao A large matryoshka structure within a 0. Researchers sliced ultra-thin layers of rock and used light to illuminate the microscopic structures inside these tiny fossils.
The oldest rocks in the world occur in the Canadian Shield. Their ages have been calculated from precisely measured ratios of the radioactive decay of trace amounts of certain isotopes in the rock sample. The ratio of… The Precambrian environment Several rock types yield information on the range of environments that may have existed during Precambrian time.
Evolution of the atmosphere is recorded by banded-iron formations BIFs , paleosols buried soil horizons , and red beds, whereas tillites sedimentary rocks formed by the lithification of glacial till provide clues to the climatic patterns that occurred during Precambrian glaciations. Paleogeography One of the most important factors controlling the nature of sediments deposited today is continental drift. This follows from the fact that the continents are distributed at different latitudes, and latitudinal position affects the temperature of oceanic waters along continental margins the combined area of the continental shelf and continental slope ; in short, sedimentary deposition is climatically sensitive.
Students learn about the development of the geologic time scale, the major time periods in earth’s history, and the role fossils play in this history.
It is a trick question. You cannot do it. There is no convincing someone who has his mind made up already. But sometimes, it is even worse. Sometimes, when you point out a fossil that falls into the middle of a gap and is a superb morphological and chronological intermediate, you are met with the response: You are losing ground! Duane Gish of the Institute for Creation Research ICR regularly trots out the “bossie-to-blowhole” transition to ridicule the idea that whales could have evolved from terrestrial, hooved ancestors.
There simply are no transitional forms in the fossil record between the marine mammals and their supposed land mammal ancestors. It is quite entertaining, starting with cows, pigs, or buffaloes, to attempt to visualize what the intermediates may have looked life. Of course, for many years the fossil record for the whales was quite spotty, but now there are numerous transitional forms that illustrate the pathway of whale evolution. Recent discoveries of fossil whales provide the evidence that will convince an honest skeptic.
Radioactive Dating Game
Stefen Chow Smithsonian Magazine Subscribe December In a pine forest in rural northeastern China, a rugged shale slope is packed with the remains of extinct creatures from million years ago, when this part of Liaoning province was covered with freshwater lakes. Volcanic eruptions regularly convulsed the area at the time, entombing untold millions of reptiles, fish, snails and insects in ash. I step gingerly among the myriad fossils, pick up a shale slab not much larger than my hand and smack its edge with a rock hammer.
A seam splits a russet-colored fish in half, producing mirror impressions of delicate fins and bones as thin as human hairs.
Learn about different types of radiometric dating, such as carbon dating. Understand how decay and half life work to enable radiometric dating. Play a game that tests your ability to match the percentage of the dating element that remains to the age of the object.
A sedimentary rock is just what it sounds like: Sedimentary rocks can consist of sand, clay, chalk and fossils and as a marine geologist I find sedimentary rocks very fascinating! Some may think that sedimentary rocks is a bit dull since sedimentary rocks isn’t created by violent and exciting volcano eruptions from the Earths mantle like the igneous rocks. No, sedimentary rocks have another type of fascinating origin and every single rock tells a story if you just know how to “read” the rock!
That is one of the fascinating thing with sedimentary rocks! The other exciting part with sedimentary rocks is that they tell us about Earths history! I will tell you a little about how to do read the rocks and I hope it will help you to see sedimentary rocks in nature in a new way! Every single particle in a sedimentary rock initially comes from a rock or as soil on land.
By time, the rock is broken down into small particles by weathering and the small particles are transported away. Sometimes the transportation distance is long and sometimes shorter. And most sedimentary rocks consists of small particles that have a long and fascinating story to tell from their long journey behind them. Read on and you will know why and how!