Radiometric Dating and the Geological Time Scale

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. A common form of criticism is to cite geologically complicated situations where the application of radiometric dating is very challenging. These are often characterised as the norm, rather than the exception. I thought it would be useful to present an example where the geology is simple, and unsurprisingly, the method does work well, to show the quality of data that would have to be invalidated before a major revision of the geologic time scale could be accepted by conventional scientists.

Radiometric Dating and the Geological Time Scale

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 of the greatest mysteries in reconstructing the history of life on Earth has been the apparent absence of fossils dating back more than million years.

January Fossils provide a record of the history of life. Smith is known as the Father of English Geology. Our understanding of the shape and pattern of the history of life depends on the accuracy of fossils and dating methods. Some critics, particularly religious fundamentalists, argue that neither fossils nor dating can be trusted, and that their interpretations are better.

Other critics, perhaps more familiar with the data, question certain aspects of the quality of the fossil record and of its dating. These skeptics do not provide scientific evidence for their views. Current understanding of the history of life is probably close to the truth because it is based on repeated and careful testing and consideration of data. The rejection of the validity of fossils and of dating by religious fundamentalists creates a problem for them:

Could the prehistoric teeth fossils dating back 9.7 million years really rewrite human history?

Sandwich bags Sand Two different colored beads for convenience, I will use the colors blue and black in the description below large enough not to fall through the sieve Containers to collect sand Prep work: Place a cup of sand each in 15 sandwich bags or how many will work for your classroom. Put beads into each bag in different amounts 5 bags will have anywhere from 1 to 30 black beads [labeled Cores ], 5 bags will have a mixture of black and blue beads [labeled Cores ] , 5 bags will have anywhere from 1 to 30 blue beads [labeled Cores ].

Write on the board that blue beads represent a foraminifer species that lived million years ago and black beads are a foraminifer species that lived million years ago. Tell them Core 1 is from the core closest to the surface and Core 15 is from the deepest core.

The CO2 Record in Plant Fossils. Plant fossils obtained from sedimentary rocks and peat deposits are a relatively new tool being used to unravel Earth’s carbon dioxide (CO2) history. Tiny pores on plant leaves and needles called stomata regulate carbon dioxide absorption and water vapor release. Stomata numbers decrease during times of high atmospheric CO2, and increase when atmospheric CO2 is.

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.

Instead they have to share electrons in molecules to get the correct number of electrons in their outside electron layer. Since we only have to look at the atom that is in the center of the molecule to find out it’s shape, we will concentrate only on Carbon and Oxygen. All the molecules illustrated on this page either have a Carbon or an Oxygen as the center atom. Carbon will especially be of interest since Carbon is the center atom for all the different Amino Acids.

Both Carbon and Oxygen have a deficiency. Neither C nor O have the proper number of electrons in their outside electron layer.

Fossil Inferences

Recent Fossils Grand Canyon has so much more than pretty scenery. It contains an amazing diversity of rock formations with an abundance of fossils hidden within. The sedimentary rocks exposed throughout the canyon are rich with marine fossils such as crinoids, brachiopods, and sponges with several layers containing terrestrial fossils such as leaf and dragonfly wing impressions, and footprints of scorpions, centipedes, and reptiles.

Ancient fossils preserved in the rock layers range from algal mats and microfossils from Precambrian Time 1, million to million years ago to a multitude of body and trace fossils from the Paleozoic Era million years ago. What about dinosaur fossils? Not at Grand Canyon!

Articles home page Creation vs. Evolution 0. Introduction and table of contents The following is an organized presentation on the creation vs. evolution controversy.

Earliest known Homo sapiens fossils discovered This is , years older than previously discovered fossils of Homo sapiens that have been securely dated. The discovery was presented in a study in the journal Nature on Wednesday. This marks the first discovery of such fossils in north Africa, and widens the “cradle of mankind” to encompass all of Africa, the researchers said. Previous finds were in south or east Africa. The fossils, including a partial skull and a lower jaw, belong to five different individuals including three young adults, an adolescent and a child estimated to be 8 years old.

Stone tools, animal bones and evidence of fire were also found within the same layer at the site. But what the researchers found to be most remarkable about these fossils is that they capture a moment in time of evolution.

Prehistoric Fossils Dating Back 9.7m Years Could Rewrite History Of Where Humans Came From

After that comes a more difficult process: Finding a fossil merely places one organism within a time span. Finding many organisms places the group within a time span. Determining the actual existence-span of the species is very approximate. If the fossils are relatively rare, the actual existence-span may be much greater that the fossil record indicates. Even if the fossils are relatively abundant during the species’ heyday, the number of organisms may have been small during the time of its appearance on Earth and during its demise.

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.

Bacterial sulfate reduction BSR. It is also a well known deposit in China. The large scale of the mineralization and especially the huge volume of H2S that was required to precipitate the Zn-Pb sulfide are of great interest to ore geologists. Ore microscopy shows microbial structures such as framboidal sphalerite, spherical aggregates of galena-sphalerite, oolite sphalerite, dendritic colloidal sphalerite-pyrite, metacolloidal sphalerite-pyrite, multinuclear-metacolloidalring-like sphalerite-pyrite, botryoidal sphalerite-pyrite, framboidal pyrite and bacterial plate-like of galena-sphalerite.

Detailed observations and analyses of the microbial structures at micron to nanometer scales by field emission scanning electron microscopy FESEM and energy dispersive spectrometry EDS reveal that the bacteria fossils are composed of sphalerite, galena or pyrite or of multiple sulfide minerals with calcite and that they are distributed in bacterial colonies in the ore. The individual bacteria fossils are spherical, botryoidal or ring-like with a diameter of — nm.

Filamentous, mucoid and tubular extracellular polymeric substances EPS are commonly observed that are closely associated with, and have the same composition as, the bacteria fossils. Previous analyses have shown that the Zn-Pb mineralization was formed at a shallow depth and low temperature with barely visible hydrothermal alteration, the presence of evaporitic sulfate layers and paleo-oil reservoir characteristics.

Oldest Homo sapiens fossils discovered

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.

“The origin of life, at least on a planet like ours, is a lot faster, and you think a lot easier than anyone had imagined. To the extent that that is true, life ought to be abundant in the.

Important We believe any unbiased reader will realize that we were fair with our treatment of the two models in the table above. Yet, although the theory of evolution matches the facts in some cases, evolution is still an unproven theory. By now, you may believe it should be your first choice also. Unlike many others that preceded us, we attempted to find a clear defense of evolution for two reasons: To keep from being accused of bias. To keep from making claims that someone could refute later.

Even though there are a great number of claims in books and on the Internet, we could find no scientific, testable facts that support the theory of evolution. The best site we could find was at The University of California at Berkeley. If you are interested, click here to examine the scientific evidence recorded at UC Berkeley yourself. It includes lots of pictures, links to other pages, and scientific names. The site is very interesting and informative.

Jean & Ric Edelman Fossil Park at Rowan University

The stable form of carbon is carbon 12 and the radioactive isotope carbon 14 decays over time into nitrogen 14 and other particles. Carbon is naturally in all living organisms and is replenished in the tissues by eating other organisms or by breathing air that contains carbon. At any particular time all living organisms have approximately the same ratio of carbon 12 to carbon 14 in their tissues. When an organism dies it ceases to replenish carbon in its tissues and the decay of carbon 14 to nitrogen 14 changes the ratio of carbon 12 to carbon

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.

Fossil Record The cyanobacteria have an extensive fossil record. The oldest known fossils, in fact, are cyanobacteria from Archaean rocks of western Australia, dated 3. This may be somewhat surprising, since the oldest rocks are only a little older: Cyanobacteria are among the easiest microfossils to recognize. Morphologies in the group have remained much the same for billions of years, and they may leave chemical fossils behind as well, in the form of breakdown products from pigments.

Small fossilized cyanobacteria have been extracted from Precambrian rock, and studied through the use of SEM and TEM scanning and transmission electron microscopy. Pictured above are two kinds cyanobacteria from the Bitter Springs chert of central Australia, a site dating to the Late Proterozoic, about million years old. On the left is a colonial chroococcalean form, and on the right is the filamentous Palaeolyngbya.

Many Proterozoic oil deposits are attributed to the activity of cyanobacteria, such as Gloeocapsomorpha. Small concentrically layered structures called pisolites are also the result of fossilized bacteria. Cyanobacteria are otherwise rarely preserved in rocks other than chert, though some possible blue-green bacteria have been recovered from shale. At right is a layered stromatolite, produced by the activity of ancient cyanobacteria.

The layers were produced as calcium carbonate precipitated over the growing mat of bacterial filaments; photosynthesis in the bacteria depleted carbon dioxide in the surrounding water, initiating the precipitation.

Fossil Inferences

Human Evolution Evidence Evidence of Evolution Scientists have discovered a wealth of evidence concerning human evolution , and this evidence comes in many forms. Thousands of human fossils enable researchers and students to study the changes that occurred in brain and body size, locomotion, diet, and other aspects regarding the way of life of early human species over the past 6 million years.

Millions of stone tools, figurines and paintings, footprints, and other traces of human behavior in the prehistoric record tell about where and how early humans lived and when certain technological innovations were invented. Study of human genetics show how closely related we are to other primates — in fact, how connected we are with all other organisms — and can indicate the prehistoric migrations of our species, Homo sapiens, all over the world.

Advances in the dating of fossils and artifacts help determine the age of those remains, which contributes to the big picture of when different milestones in becoming human evolved.

Creation Versus Evolution: We compare the theory of evolution with the Bible’s creation account in easy-to-understand terms, using evidence from the fields of paleontology, geology, biology, and provide links and a bibliography for those who want to study both sides of the issue.

The property of a European gentleman. Originally found in Western Sumatra at a depth of 40 m. Tennessee, Carboniferous Period, million years BP. The large stump of pleasing grey and ochre color with a relatively smooth surface in which the vesicles typical of the species are clearly visible. Shown at the University of Tennessee where it was identified and confirmed authentic by them.

Extremely rare complete Lepidodendron stump. Lepidondendrons were among the first large trees to appear on earth. These long extinct tall spore-bearing trees were related to modern club mosses. They stood in a dense, swampy forest million years ago contemporaneous with the first appearance of land animals. These Giant Club Moss trees somewhat resembled modern palms crowned with spiky fronds.

Fossils and dating methods (ANT)