Relative Dating of Rock Layers
Presentation on theme: "I. Principles of Relative Dating"— Presentation transcript:
5. • Physical continuity. • Similarity of rock types. • Superposition. • Correlation by fossils. – Principle of faunal succession. – Concept of index fossil. – Fossil assemblage. • Radioisotopic dating-comparisons. Timing of event on the regional scale: Correlation. Correlation of strata: Colorado Plateau. superposition minimoving.info ( bytes), Superposition of rock units is a very simple and straightforward method of relative age determination. The principle states that in a sequence of undeformed sedimentary rocks the oldest beds are at the bottom and the youngest ones are at the top. Underlying assumptions are. 2 Oct Relative Dating (Steno's Laws). Long before geologists tried to quantify the age of the Earth they developed techniques to determine which geologic events preceded another, what are termed "relative age” relationships. These techniques were first articulated by Nicolas Steno, a Dane living in the Medici.
We think you have liked this presentation. If you wish to download it, please recommend it to your friends in any social system. Share buttons are a little bit lower. Published by Rachael Worth Modified over 3 years ago. Principles of Relative Dating A. Principles of Relative Dating B. Principle of Superposition In a horizontal sequence of rock layers: If rocks are tilted, look for mudcracks, graded beds, ripple marks, cross bedding, or vesicles to determine the up direction.
Principle of Superposition If rocks are tilted, look for sedimentary structures such as, mudcracks, graded beds, ripple marks, cross bedding, or vesicles to determine the up direction.
Principles of Relative Dating C. Principle of Cross-Cutting Relationships Any intrusive formation dike, sill, batholith is younger than the rock it cuts across Faults are younger than the rocks they cut and displace. Principles of Relative Dating D. By carefully 5 Principles Of Relative Age Dating, we have found that each trash pit shows a sequence of layers.
Although the types of trash in each pit is quite variable, each layer has a distinctive kind of trash that distinguishes it from other layers in the pits. Principles of Relative Dating.
Principles of Relative Dating E. Principle of Faunal Successions Fossils: Principles of Relative Dating II. Disconformity Occurs between parallel layers of sedimentary rock or lava flows Time missing using the fossil record Layer below shows erosion - irregular surface.
Nonconformity Click between an unlayered body of plutonic igneous or metamorphic rock and an overlying layered sequence of sedimentary rock layers Underlying rock shows signs of erosion, e.
Principles of Relative Dating Relative dating animation. Principles of Relative Dating Horizontality, superposition, unconformities, cross-cutting relations, and faunal succession.
Relative Dating using Weathering Weathering is a function of time In one location, other factors like climate, organisms, and rock compositions will be held constant A.
Weathering Rinds Rind of chemical weathering formed as water penetrates into rock and minerals are altered to more stable minerals Rind gets thicker with time. Relative Dating by Weathering Weathering is a function of time B. Relative Dating by Weathering Weathering is a function of time C.
Proterozoic and Archean Eons Angular Unconformity: Ordovician and Silurian missing Redwall Limestone: Devonian and Mississipian Disconformity: Principle of Horizontality 2.
Many of the same principles are applied. Interval of time when the earth's magnetic field is oriented so that the magnetic north pole is approximately in the same position as the geographic north pole neutrons: The principle states that in a sequence of undeformed sedimentary rocks the oldest beds are at the bottom and the youngest ones are at the top.
Principle of Superposition Angular unconformity Nonconformity Disconformity 3. Principles of Relative Dating IV. Problem set, due Monday Http://minimoving.info/lub/best-dating-site-for-retired-professionals-consulting-agreement.php 2: Come get help from me if you need it!
I will walk through it with you! Principles of Relative Dating Long before radiometric dating was possible, important principles of relative ages of rock units were established. Principle of original horizontality: Because sedimentary particles settle under the influence of gravity, sedimentary layers of rock are deposited horizontally. Sedimentary rock layers that are not horizontal have been folded or tilted by a tectonic event.
Deposition of the sedimentary rocks predates the tectonic event. Principles of Relative Dating 2. In any sequence of undisturbed layers of sedimentary rocks, the oldest layer is on the bottom and successively higher layers are successively younger.
Layers later can be tilted and deformed, even turned upside down by later tectonic events. The original top 5 Principles Of Relative Age Dating bottom of a sedimentary unit often can be determined from sedimentary structures, such as mud cracks, cross beds, and ripple marks.
Principles of Relative Dating 3. Fragments of rock that are enclosed within another rock are older than the enclosing rock. Principles of Relative Dating 4.
Relative Dating Practice 2015
If an igneous intrusion or a fault cuts a rock unit, then the rock unit is older than the intrusion or fault. Evidence for intrusion can include baking of the intruded rocks.
If you date the igneous rock, you have a limit on the youngest absolute possible age of the rocks minimum age, i. Principles of Relative Dating 5. Superposition of volcanic rocks: If sedimentary rocks are overlain by a lava flow, they must be older than the flow.
This content is currently under construction. Learning Outcomes After watching this video lesson, you'll be able to: Once one reversal has been related to the GPTS, the numerical age of the entire sequence can be determined. A region where lines of force move electrically charged particles, such as around a magnet, through a wire conducting an electric current, or the magnetic lines of force surrounding the earth magnetism:
If you date the igneous rock, you know the youngest possible absolute age for the sedimentary rocks. Draw and label an angular unconformity. Now for a little more complicated example. How Old is the Earth i. Weathering of rocks and Sediment Production ii. How Click is the Earth iii.
References and Recommended Reading
Relative Dating and Sequencing Relative vs. When the age of rock is compared to the ages of other rocks or events in geological time. Can determine which layers are older than others. Concepts and Principles Geologic Time. Bell Ringer What is the theory of evolution? How do fossil records prove this theory? Give two examples of animal fossils found that give evidence to support.
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