Interpreting Geologic Sections in Structural Geology

Interpreting Geologic Sections in Structural Geology

Numeric absolute dating Uses radiogenic isotopes Decay rates are known, constant 3 decay methods Alpha decay Beta decay Electron capture About PowerShow. Whether your application is business, how-to, education, medicine, school, church, sales, marketing, online training or just for fun, PowerShow. And, best of all, most of its cool features are free and easy to use. You can use PowerShow. Or use it to find and download high-quality how-to PowerPoint ppt presentations with illustrated or animated slides that will teach you how to do something new, also for free. Or use it to upload your own PowerPoint slides so you can share them with your teachers, class, students, bosses, employees, customers, potential investors or the world. That’s all free as well! For a small fee you can get the industry’s best online privacy or publicly promote your presentations and slide shows with top rankings. But aside from that it’s free.

Relative and Absolute Geologic Time – PowerPoint PPT Presentation

Radiometric dating In , shortly after the discovery of radioactivity , the American chemist Bertram Boltwood suggested that lead is one of the disintegration products of uranium, in which case the older a uranium-bearing mineral the greater should be its proportional part of lead. Analyzing specimens whose relative geologic ages were known, Boltwood found that the ratio of lead to uranium did indeed increase with age.

After estimating the rate of this radioactive change, he calculated that the absolute ages of his specimens ranged from million to 2. Though his figures were too high by about 20 percent, their order of magnitude was enough to dispose of the short scale of geologic time proposed by Lord Kelvin. Versions of the modern mass spectrometer were invented in the early s and s, and during World War II the device was improved substantially to help in the development of the atomic bomb.

Some examples of events listed on the geologic time scale include the first appearance of plant life on Earth, the first appearance of animals on Earth, the formation .

April Koch April teaches high school science and holds a master’s degree in education. Discover how geologists study the layers in sedimentary rock to establish relative age. Learn how inclusions and unconformities can tell us stories about the geologic past. We’ll even visit the Grand Canyon to solve the mystery of the Great Unconformity! Your goal is to study the smooth, parallel layers of rock to learn how the land built up over geologic time. Now imagine that you come upon a formation like this: Example of a rock layer that is not smooth or parallel What do you think of it?

How do you study it? How can you make any conclusions about rock layers that make such a crazy arrangement? Geologists establish the age of rocks in two ways: Numerical dating determines the actual ages of rocks through the study of radioactive decay. Relative dating cannot establish absolute age, but it can establish whether one rock is older or younger than another.

How Old is the Earth

Roman poet Lucretius, intellectual heir to the Greek atomists, believed its formation must have been relatively recent, given that there were no records going back beyond the Trojan War. The Talmudic rabbis, Martin Luther and others used the biblical account to extrapolate back from known history and came up with rather similar estimates for when the earth came into being. Within decades observation began overtaking such thinking.

In the s Nicolas Steno formulated our modern concepts of deposition of horizontal strata.

Events can be the deposition of a sedimentary layer, the eruption of a lava flow, the intrusion of magma to form a batholith, a fault (break) in the rock that shifts one side relative to the other side (and causes an earthquake), a fold that bends and distorts rock layers, or any number of other geologic processes.

Have available the following items: A colorful geological map, preferably of your area on wall, or as an overhead color transparency. The Deep Time activity envelopes one for each team of two, with isotope strips in them The Deep Time handouts: The pre- and post-test quizzes, ready to hand out optional A scaled time-line for the solar system around the classroom, if possible see our Time Machine lesson.

How sure are we about these ages? How do we measure the ages of rocks? Count “atoms” in simulated rock samples of different “ages”. Students relate half-lives of radioisotopes to the application of dating rocks.

How is radioactive dating used to determine the age of an object?

Slowly and painstakingly, geologists have assembled this record into the generalized geologic time scale shown in Figure 1. This was done by observing the relative age sequence of rock units in a given area and determining, from stratigraphic relations, which rock units are younger, which are older, and what assemblages of fossils are contained in each unit.

Using fossils to correlate from area to area, geologists have been able to work out a relative worldwide order of rock formations and to divide the rock record and geologic time into the eras, periods, and epochs shown in Figure 1. The last modification to the geologic time scale of Figure 1 was in the s, before radiometric dating was fully developed, when the Oligocene Epoch was inserted between the Eocene and the Miocene.

The textbooks focus on relative dating, based on the layering of the rocks, and radiometric dating. Relative ages are assigned to rocks based on the idea that rock layers lower in the strata were deposited before rock layers that are higher.

In geology , rock or superficial deposits, fossils and lithologies can be used to. Start studying Geology note quiz- Dating of Rocks , Fossils and geologic events. Learn vocabulary, terms, and more with flashcards, games, and other study. There are 8 layers, and they should be numbered 1 through 8, from the. This activity on determining age of rocks and fossils is intended for 8th or 9th grade. The method of reading the order is called. Most absolute dates for rocks are obtained with radiometric methods.

In fact, even in younger rocks , absolute dating is the only way that the. Relative age dating of geologic cross sections..

Radiometric Dating Does Work!

Potential of abundant, environmentally harmless energy technology , which already exists My strategy for manifesting that energy event for humanity’s and the planet’s benefit. I w as born in In that same year, I had my cultural and mystical awakenings. During my second year of college, I had my first existential crisis and a paranormal event changed my studies from science to business.

These correlations led to the construction of the geologic time scale, a global record of rocks and their relative ages. However, before geologists can correlate the ages of rocks from different areas, they must first figure out the ages of rocks at a single location.

Thus we do not know the numeric age of any given layer. The civilizations that deposited the trash had a culture and industrial capabilities that evolved through time. The oldest inhabitants used primitive stone tools, later inhabitants used cups made of ceramics, even later inhabitants eventually used tin cans and then changed to Aluminum cans, and then they developed a technology that used computers. This shows that society has evolved over the years. Similar cultures must have existed in both areas and lived at the same time.

Thus we can make correlations between the layers found at the different sites by reasoning that layers containing similar distinctive discarded items artifacts were deposited during the same time period. Because the Ceramic Cups layer is found at the Tulane site, but not at the Zoo site, the civilization that produced the Ceramic cups probably did not live in the Zoo area. Thus, we can recognize a break in the depositional sequence at the Zoo site. The surface marking the break in deposition would be called an unconformity in geologic terms, and represents time missing from the depositional record.

The trash pits contain some clues to numeric age: The Tulane trash pit has an old license plate in the Tin Cans layer.

Radiometric Dating and the Geological Time Scale

Radiometric Dating Does Work! Radiometric dating of rocks and minerals using naturally occurring, long-lived radioactive isotopes is troublesome for young-earth creationists because the techniques have provided overwhelming evidence of the antiquity of the earth and life. Some so-called creation scientists have attempted to show that radiometric dating does not work on theoretical grounds for example, Arndts and Overn ; Gill but such attempts invariably have fatal flaws see Dalrymple ; York and Dalrymple

GEOLOGIC DATING/RELATIVE AGES OF ROCKS. OBJECTIVES: To be able to determine the sequence of geologic events as recorded in the rocks of different areas, Using Figure and the data in the preceding table, plot the above data on the following graph (Figure ). Draw a SMOOTH CURVE connecting the points.

No reproduction may be made without prior approval from the author Dr. Relative Dating of Geologic Cross-Sections: Cliffs, road cuts, and non-vegetated landscapes allow us glimpses into geology which is often hidden from view. Cliffs and road cuts are “side views” or “geologic cross-sections” of the topography which show the relative positions of various rock layers and structures at a given spot.

Applying the principles of relative dating to these rock exposures also called “outcrops” , we can reconstruct the sequence of events that created the geologic features which we see. Events can be the deposition of a sedimentary layer, the eruption of a lava flow, the intrusion of magma to form a batholith, a fault break in the rock that shifts one side relative to the other side and causes an earthquake , a fold that bends and distorts rock layers, or any number of other geologic processes.

Just as Sherlock Holmes used his power of observation to decipher the clues to a suspect’s past actions, we will let the blemishes and behaviors of the rocks tell us their past story. Am I getting too carried away here? Remember that relative dating involves determining “which came first” rather than “exactly when did this happen.

To review our principles of relative dating as applied to such geologic cross-sections, we will make use of a neat learning tool available on the Internet. Click to access the activities related to the interpretation of geologic sequences.

How Science Figured Out the Age of Earth

Geologic Time Scale Up: Common and Scientific Names [page ] Geologic time correlates rocks and time. The modern geologic time scale shown in Figure A1 was nearly complete by the end of the 19th century and was based on stratigraphic and fossil studies in northern Europe and the United States. The scale, developed before absolute dating techniques were discovered, is a relative geologic scale that provides a standard of reference for dating rocks throughout the world.

3. EXPLAIN: Do the Deep Time lesson, which emphasizes why we are so confident of geological age dates. 4. ELABORATE: Do the Virtual Age Dating Tutorial (online), for further reinforcing of half-life concept and how this is applied to dating rocks.

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.

High School Earth Science/Relative Ages of Rocks

After layers A-B-C were present, intrusion D cut across all three. Fault E formed, shifting rocks A through C and intrusion D. Weathering and erosion created a layer of soil on top of layer A.

figure out what happened over the billion years of Earth’s history. The oldest evidence of life is from about billion years ago, but life may be even older.

Students know the evidence from geological studies of Earth and other planets suggests that the early Earth was very different from Earth today. A geologic time scale was developed that showed the sequence, or order, of events based on several principles of relative dating. What are these principles? What part do fossils play? In this chapter you will learn the answers to these questions.

Powell realized that the evidence for an ancient Earth was concealed in its rocks. B Start of the expedition from Green River station.

How Do Scientists Determine the Age of Dinosaur Bones?

What does the principle of uniformitarianism mean? The processes that we see happening today happened in the same way in the past. What are geologic hazards that we might encounter when we build houses?

What was the series of ideas & events that led to the discovery of plate o Radiocarbon dating of organic material in trenches through faults that have experienced recent EQs [PPT] B. Direct measurement Lecture Notes: Plate Tectonics.

Introduction to Geology Chapter 2 – Basic Geologic Principles The science of geology is founded on basic principles that are useful for making observations about the world around us. This chapter presents a mix of information that is essential fundamental to all following chapters. This chapter is an introduction to rocks and minerals, and the rock cycle. Basic chemistry is important to all sciences, especially geology!

Everything around us is made of chemical compounds that have testable and identifying characteristics, allowing them to be classified, and their age determined. This also applies to rocks, minerals, and derivative materials such as sediments and soil. The chemical composition of Earth’s crust has similarities with other stony planets, with silicate-rich rocks being dominant in most locations on the surface. In addition, basic geologic principles can be applied to resolving the order of events leading to the formation of rocks and landscape features.

This section presents many basic concepts that are universal to all physical sciences. Click on thumbnail images for a larger view. Layered rocks in a sea cliff in Encinitas, CA with an angular unconformity. What are “rocks” and “minerals” – explain the differences. Describe essential concepts of chemistry related to earth materials. What is the chemical and mineral composition of the Earth’s crust?

Relative Dating Practice 2015



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