5. To use radiometric dating and the principles of determining relative age to show how ages of To start, place all your activity pieces with U facing up. relative ages from sequence of rock deposition. • Initial Horizonality Principle applies to sedimentary rocks formed in an aqueous environment Page 5. Scotland. Principles used to determine relative age 5. • Physical continuity. • Similarity of rock types. • Superposition Radioisotopic dating-comparisons.
Relative Age Dating Activity. - ppt download
Granites can intrude into other rocks. They may be the youngest rock even though they may be on the bottom of your geologic diagram.
Relative Age Dating Activity.
Look carefully for the granitic pattern see below and for irregular contacts between the granite and the preexisting country rock see Activity figure 2, below. This is shown as a starred pattern in the adjacent rock pattern. Metamorphic rocks are preexisting rocks that have been metamorphosed changed into different rocks by large amounts of heat and pressure in a region.
These rocks have usually been deformed by large, mountain forming events, and therefore if they are in contact with unchanged sedimentary rocks, they are usually the oldest rocks in the sequence.
If the sedimentary rocks had been in place when the metamorphism occurred, they also would be metamorphosed! Always look for the metamorphic pattern see below to determine if there is a metamorphic rock in your sequence.
Now, familiarize yourself with the rock patterns: Answer the following questions based on your reading. Which of the five principles of relative dating apply to sedimentary rocks?
I. Principles of Relative Dating - ppt video online download
Are only sedimentary rocks used for relative age determinations? Principles of Relative Dating Relative dating animation 20 I. Principles of Relative Dating Horizontality, superposition, unconformities, cross-cutting relations, and faunal succession 21 I. 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 22 I. Relative Dating by Weathering Weathering is a function of time B. Relative Dating by Weathering Weathering is a function of time C. Principles of Relative Dating 25 26 Grand Canyon: Proterozoic and Archean Eons Angular Unconformity: Ordovician and Silurian missing Redwall Limestone: Devonian and Mississipian Disconformity: Principle of Horizontality 2.
Principle of Superposition Angular unconformity Nonconformity Disconformity 3. Faunal Succession 28 I. Principles of Relative Dating IV. Problem set, due Monday Page 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.
A single watch or clock for the entire class will do. Return to top PART 1: After students have decided how to establish the relative age of each rock unit, they should list them under the block, from most recent at the top of the list to oldest at the bottom.
The teacher should tell the students that there are two basic principles used by geologists to determine the sequence of ages of rocks.
What's Up: Relative Dating Acitivity
Younger sedimentary rocks are deposited on top of older sedimentary rocks. Principle of cross-cutting relations: Any geologic feature is younger than anything else that it cuts across.
For example, U is an unstable isotope of uranium that has 92 protons and neutrons in the nucl eus of each atom. Through a series of changes within the nucleus, it emits several particles, ending up with 82 protons and neutrons. This is a stable condition, and there are no more changes in the atomic nucleus.
A nucleus with that number of protons is called lead chemical symbol Pb.Principles of Relative Dating 1 - Superposition, Horizontality, Cross-cutting
The protons 82 and neutrons total This particular form isotope of lead is called Pb U is the parent isotope of Pb, which is the daughter isotope. Many rocks contain small amounts of unstable isotopes and the daughter isotopes into which they decay. Where the amounts of parent and daughter isotopes can be accurately measured, the ratio can be used to determine how old the rock is, as shown in the following activities.
That chance of decay is very small, but it is always present and it never changes. In other words, the nuclei do not "wear out" or get "tired". If the nucleus has not yet decayed, there is always that same, slight chance that it will change in the near future. Atomic nuclei are held together by an attraction between the large nuclear particles protons and neutrons that is known as the "strong nuclear force", which must exceed the electrostatic repulsion between the protons within the nucleus.
In general, with the exception of the single proton that constitutes the nucleus of the most abundant isotope of hydrogen, the number of neutrons must at least equal the number of protons in an atomic nucleus, because electrostatic repulsion prohibits denser packing of protons. But if there are too many neutrons, the nucleus is potentially unstable and decay may be triggered. This happens at any time when addition of the fleeting "weak nuclear force" to the ever-present electrostatic repulsion exceeds the binding energy required to hold the nucleus together.
In other words, during million years, half the U atoms that existed at the beginning of that time will decay to Pb This is known as the half life of U- Many elements have some isotopes that are unstable, essentially because they have too many neutrons to be balanced by the number of protons in the nucleus.