Resources Introduction The methods used by archaeologists to gather data can be applied to any time period, including the very recent past. One archaeologist in the U. Over the past years archaeologists have developed many effective methods and techniques for studying the past. Archaeologists also rely upon methods from other fields such as history, botany, geology, and soil science. In this section of Methods of Gathering Data you will learn how archaeologists gather and analyze information by utilizing historical research techniques, field methods for data recovery, and laboratory analyses. Back to top Historical Research Techniques Every archaeology project begins with a research design —a plan that describes why the archaeology is being done, what research questions it hopes to answer, and the methods and techniques that will be used to gather and analyze the artifacts and other archaeological materials.
They quickly hardened into the dense, black rock called basalt Figure 3. Further thick sediment layers were soon deposited on top of them. Determining the Ages of Rocks Can the exact age of these basalt lavas be determined by their position in the Grand Canyon sequence of rock layers or by physically examining them? However, most geologists classify the Cardenas Basalt as Precambrian; that is, it is older than the so-called Cambrian rock layers such as the Tapeats Sandstone and Bright Angel Shale that contain fossils of marine creatures such as trilobites Figure 4.
But the rock itself looks like many other basalts found all around the world Figure 5. With the application of radioactivity to the dating of rocks, these geologists believe they now have a virtually foolproof method for determining exact ages.
Earth is constantly bombarded with primary cosmic rays , high energy charged particles — mostly protons and alpha particles. These particles interact with atoms in atmospheric gases, producing a cascade of secondary particles that may in turn interact and reduce their energies in many reactions as they pass through the atmosphere. By the time the cosmic ray cascade reaches the surface of Earth it is primarily composed of neutrons.
In rock and other materials of similar density, most of the cosmic ray flux is absorbed within the first meter of exposed material in reactions that produce new isotopes called cosmogenic nuclides. At Earth’s surface most of these nuclides are produced by neutron spallation. Using certain cosmogenic radionuclides , scientists can date how long a particular surface has been exposed, how long a certain piece of material has been buried, or how quickly a location or drainage basin is eroding.
The cumulative flux of cosmic rays at a particular location can be affected by several factors, including elevation, geomagnetic latitude, the varying intensity of the Earth’s magnetic field , solar winds, and atmospheric shielding due to air pressure variations. Rates of nuclide production must be estimated in order to date a rock sample. These rates are usually estimated empirically by comparing the concentration of nuclides produced in samples whose ages have been dated by other means, such as radiocarbon dating , thermoluminescence , or optically stimulated luminescence.
The excess relative to natural abundance of cosmogenic nuclides in a rock sample is usually measured by means of accelerator mass spectrometry.
Age of the Earth: strengths and weaknesses of dating methods
Over the next century, amateur and official meteorologists continued taking observations in settlements dotted around the continent, providing documentary evidence of climate variability in Australia. Unfortunately for modern-day scientists, there was no common standard for observing equipment during the colonial period. Any number of instrument configurations were used, including—perhaps iconically—thermometers housed in beer crates on outback verandas.
By , however, the newly formed Australian Bureau of Meteorology had established standardised equipment in many parts of the country Over the past century, the Bureau has expanded, developed and advanced its network of observing sites. In , the Bureau had temperature recording sites and nearly rain gauges operating across Australia. Climate records, like this one from September , are archived by the Bureau of Meteorology.
Post Card History and Dating Methods. Although the world’s first picture post cards date from the s to the mids, post cards, as we know them, came into being in the United States about
Reference to a case where the given method did not work This is perhaps the most common objection of all. Creationists point to instances where a given method produced a result that is clearly wrong, and then argue that therefore all such dates may be ignored. Such an argument fails on two counts: First, an instance where a method fails to work does not imply that it does not ever work. The question is not whether there are “undatable” objects, but rather whether or not all objects cannot be dated by a given method.
The fact that one wristwatch has failed to keep time properly cannot be used as a justification for discarding all watches. How many creationists would see the same time on five different clocks and then feel free to ignore it?
Could suggest an ancient stream bed or a seashore Ripple marks on a bedding plane Sand dunes What is the most logical past environment to have produced consisting of layers of well sorted sandstone with cross beds several meters high? Mudcracks What sedimentary features is the surest indicator that the past environment was subaerial not submarine? Mud,slit, sand Proper listing of detritus terms, going from smallest to largest ripple marks created by water flowing from A to B the diagram below is a profile of false Sedimentary rocks differ from igneous rocks in that sedimentary rocks can never be crystalline in texture and igneous rocks always are crystalline.
Primary source references As a preface to this document, I want to point out that it is a shame that we have to continue to refute the same arguments that evolutionists keep bringing up over and over again in their attempts to argue against the fact of creation, which fact has been well established since the day the earth was created ex nihilo several thousand years ago.
It is also a shame that the masses have bought all this based on some circular reasoning about fossils, where fossils tend to be found buried, similarities between various life forms, the presence of certain decay products in rocks, and other inherently speculative arguments about the past, based on phenomena that exist in the present. If I hope to accomplish anything, it will be to simply encourage critical thinking.
One must get past the arguments ad populum that its popularity counts for something , ad hominem that if you attack the person making the argument, this counts for something , and especially ad baculum that there are people who have the clout to decree it as true , to ask the key questions and challenge the unsubstantiated assumptions and thinking of those who would hold to the evolution position.
Today there are an increasing number of anti-creationist authors who are producing books and periodicals that make this relatively brief presentation insufficient to deal with all the points in dispute. Those defending creation today who don’t have the time to devote their life’s study to gaining expertise in all fields of inquiry must principally be prepared to think critically, logically, and challenge unsubstantiated assumptions made by these people.
They must also keep a level head in the face of some vicious attacks and diatribes that will be directed against them, as is advised in the scriptures 1 Peter 3: By way of definitions, I want to point out that when I speak of “evolution,” I am referring to the popular contemporary use of the word, which in a nutshell is the belief that all life forms are related by ancestry, and that the first life form occurred spontaneously, all due to completely natural processes.
When I speak of “creation,” I am referring to the inherently obvious fact that the origin of all life forms can be attributed to a creator who purposefully created them with planning and intent, and the documented fact that this occurred over the course of a week’s time several thousand years ago. This document is not a scientific thesis, but an apologetic intended to be submitted and defended by me in an interactive, online electronic forum.
I claim no copyright on this document, and grant its use to the public domain. I have not written it with a view towards receiving any sort of financial or other personal gain, and I request that others utilizing this document do likewise. Those copying and disseminating this document shall assume full responsibility for defending it. I do not agree to defend this document in any forum that I did not submit it, due to the practical limitations of my own time.
A disconformity is a surface between parallel sedimentary beds of significantly different ages. Evidence of stream erosion or existence of a paleosol ancient soil horizon may help in recognizing a disconformity Which of the following is NOT a method to determine numerical age? Cross-cutting relations – Cross-cutting relationships are used for relative, not numerical, dating.
Carbon dating, also called radiocarbon dating, method of age determination that depends upon the decay to nitrogen of radiocarbon (carbon). Carbon is continually formed in nature by the interaction of neutrons with nitrogen in the Earth’s atmosphere; the neutrons required for this reaction are produced by cosmic rays interacting with the atmosphere.
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.
Geochronologists do not claim that radiometric dating is foolproof no scientific method is , but it does work reliably for most samples. It is these highly consistent and reliable samples, rather than the tricky ones, that have to be falsified for “young Earth” theories to have any scientific plausibility, not to mention the need to falsify huge amounts of evidence from other techniques. This document is partly based on a prior posting composed in reply to Ted Holden.
My thanks to both him and other critics for motivating me.
General considerations Distinctions between relative-age and absolute-age measurements Local relationships on a single outcrop or archaeological site can often be interpreted to deduce the sequence in which the materials were assembled. This then can be used to deduce the sequence of events and processes that took place or the history of that brief period of time as recorded in the rocks or soil.
For example, the presence of recycled bricks at an archaeological site indicates the sequence in which the structures were built. Similarly, in geology, if distinctive granitic pebbles can be found in the sediment beside a similar granitic body, it can be inferred that the granite, after cooling, had been uplifted and eroded and therefore was not injected into the adjacent rock sequence.
The Paleogeographic Method. The study of paleogeography has two principle goals. The first goal is to map the past positions of the continents.
Measurement of N, the number of 14 C atoms currently in the sample, allows the calculation of t, the age of the sample, using the equation above. The above calculations make several assumptions, such as that the level of 14 C in the atmosphere has remained constant over time. The calculations involve several steps and include an intermediate value called the “radiocarbon age”, which is the age in “radiocarbon years” of the sample: Radiocarbon ages are still calculated using this half-life, and are known as “Conventional Radiocarbon Age”.
Since the calibration curve IntCal also reports past atmospheric 14 C concentration using this conventional age, any conventional ages calibrated against the IntCal curve will produce a correct calibrated age. When a date is quoted, the reader should be aware that if it is an uncalibrated date a term used for dates given in radiocarbon years it may differ substantially from the best estimate of the actual calendar date, both because it uses the wrong value for the half-life of 14 C, and because no correction calibration has been applied for the historical variation of 14 C in the atmosphere over time.
The Paleogeographic Method The study of paleogeography has two principle goals. The first goal is to map the past positions of the continents. The second goal is to illustrate the changing distribution of mountains, lowlands, shallow seas, and deep ocean basins through time. Mapping the Past Positions of the Continents The past positions of the continents can be determined using the following five lines of evidence: By measuring the remanent magnetic field often preserved in iron-bearing rock formations, paleomagnetic analysis can determine whether a rock was magnetized near the Pole or near the Equator.
Articles home page Creation vs. Evolution 0. Introduction and table of contents The following is an organized presentation on the creation vs. evolution controversy.
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. Both the physical geologists and paleontologists could point to evidence that much more time was needed to produce what they saw in the stratigraphic and fossil records.
As one answer to his critics, Kelvin produced a completely independent estimate — this time for the age of the Sun. His result was in close agreement with his estimate of the age of the earth. The solar estimate was based on the idea that the energy supply for the solar radioactive flux is gravitational contraction.
Methods of Gathering Data
March 28, This post is about elevation measurements for exposure-dating samples, and how accurate they need to be. Basically, the main thing that controls cosmogenic-nuclide production rates is site elevation, or, more precisely, atmospheric pressure — at higher elevation, there is less atmosphere between you and the extraterrestrial cosmic-ray flux, so the production rate is higher. Thus, to compute the cosmogenic-nuclide production rate at a sample site, the first thing we need to know is the elevation.
Once we know the elevation, we can convert it to a mean atmospheric pressure using a model for how the atmospheric pressure varies with elevation, and then compute the production rate. The second one — converting an elevation to a mean atmospheric pressure during the exposure duration of the sample — is actually a fairly complicated problem and is the subject of another post , as well as a fairly large number of papers.
However, the first one — accurately measuring the elevation — ought to be pretty simple.
Historical Research Techniques. Every archaeology project begins with a research design –a plan that describes why the archaeology is being done, what research questions it hopes to answer, and the methods and techniques that will be used to gather and analyze the .
Unlike the radioactive isotopes discussed above, these isotopes are constantly being replenished in small amounts in one of two ways. The bottom two entries, uranium and thorium , are replenished as the long-lived uranium atoms decay. These will be discussed in the next section. The other three, Carbon , beryllium , and chlorine are produced by cosmic rays–high energy particles and photons in space–as they hit the Earth’s upper atmosphere.
Very small amounts of each of these isotopes are present in the air we breathe and the water we drink. As a result, living things, both plants and animals, ingest very small amounts of carbon , and lake and sea sediments take up small amounts of beryllium and chlorine The cosmogenic dating clocks work somewhat differently than the others. Carbon in particular is used to date material such as bones, wood, cloth, paper, and other dead tissue from either plants or animals.
To a rough approximation, the ratio of carbon to the stable isotopes, carbon and carbon , is relatively constant in the atmosphere and living organisms, and has been well calibrated. Once a living thing dies, it no longer takes in carbon from food or air, and the amount of carbon starts to drop with time.
Since the half-life of carbon is less than 6, years, it can only be used for dating material less than about 45, years old. Dinosaur bones do not have carbon unless contaminated , as the dinosaurs became extinct over 60 million years ago. But some other animals that are now extinct, such as North American mammoths, can be dated by carbon Also, some materials from prehistoric times, as well as Biblical events, can be dated by carbon