Crossword Puzzle for Record of Time
Topics 4-5Chronometric Techniques Parts 1-2

Across

5. A radiometric dating method based on the fact that when trace amounts of uranium-238 decay, there is a release of highly energy-charged alpha particles which burn narrow tracks, or damage trails, through glassy materials like obsidian (i.e., volcanic glass).
6. A radiometric dating method based on the fact that background radiation causes electrons to separate from their atoms and become trapped in the crystal lattice of minerals. This progressively alters the magnetic field of the material at a predictable rate. The magnetic field of the atoms in a sample is measured to determine the age. This technique is employed primarily to chronometrically date calcium carbonate in limestone, coral, teeth, and egg shells. This method is also reffered to as ESRdating.
7. Magnetic fields that are altered or formed in atoms of iron by heat in excess of 1100 F. (600 C.). Such fields line up with the magnetic field of the Earth at the time of the exposure to a high temperature.
9. A term referring to techniques for chronometric dating based on known half-lives of particular isotopes or the rate of other cumulative changes in atoms resulting from radioactivity. Examples include electron spin resonance, fission track, potassium-argon, radiocarbon, and thermoluminescence dating.
11. The point on the northern extremity of the earth where the axis of rotation is located. Compared to the magnetic north pole, this one is relatively stable.
12. Any of two or more forms of an element that differ in terms of atomic mass but have the same atomic number--for example, carbon- 12 and carbon-14.
13. A chronometric dating method based on the fact that amino acids progressively change to mirror image forms following the death of  an organism--i.e., from L-amino acid to D-amino acid forms.
14. The process by which plants, algae, and some bacteria use energy from sun light to create new organic molecules out of carbon dioxide and water.
15. The amount of time for half of the atoms of a radioactive element in a sample to decay, or fission.

Down

1. A dating technique using a research instrument primarily employed in physics to accelerate streams of charged subnuclear particles to high velocities in order to sort and analyze them. This technique is now also used to count individual carbon isotope atoms for carbon-14 dating. This method is also referred to as AMS dating.
2. The study of annual growth-rings of trees, usually for the purpose of chronometric dating logs and, subsequently, human remains and artifacts found in association with them.
3. A radiometric dating method based on the fact that potassium-40 in volcanic rock decays into argon-40 and calcium-40 at a known rate. Chronometric dates are determined by measuring the amount of argon- 40 in a sample. This method is also referred to as K-Ar dating.
4. A chronometric dating method based on the fact that the magnetic north and south poles periodically reverse.
8. A radiometric dating method based on the fact that the amount of carbon-14 steadily decreases in all organisms after death. This technique is used to provide chronometric dates for organic materials such as bone, shell, wood, and charcoal.
10. A radiometric dating method based on the fact that background radiation causes electrons to separate from their atoms and become trapped in the crystal lattice of minerals. When heated to high temperatures, the trapped electrons are released and they give off energy in the form of light. The characteristic of that light is measured to determine the age of the sample. This technique is mainly used to date pottery and rock that previously had been in an intense fire. This method is also referred to as TL dating.


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