practice, glow curves are obtained for the compressed and uncompressed samples. 

 If subjection to the high pressures causes the intensity of thermoluminescence to 

 increase in the high-temperature peaks, the initial crystallization-induced thermo- 

 luminescence has not all been annealed out, and the age cannot be determined di- 

 rectly from the values of R a and the alpha counts. If pressure does not increase 

 the thermoluminescence, or if it decreases thermoluminescence, the measurements 

 can be used for age determinations. It is clear that if later crystallizations have 

 occurred, their ages will be obtained rather than the age of the original lime- 

 stone. The age of early Tertiary limestones and older limestones as determined 

 by thermoluminescence agreed with the age determined by fossils and standard 

 geological evidence. The areas of the glow curves can be determined with an 

 error of about 10 percent or less, and the counting of the alpha particles is prob- 

 ably the least accurate measurement. Again, if uranium or other elements pro- 

 ducing alpha particles have been leached out, or if they have come in between 

 grains at a later geological period, the age determinations will be subjected to 

 serious error. 



SUMMARY The thermoluminescence of rocks and min- 



erals provides a new type of measurement for 

 crystals and minerals which may find applications in geology. The glow curves 

 are greatly affected by impurities and geological history, and they are character- 

 istic of a given sample. Most of the research has been concerned with limestones 

 and the possibilities of using thermoluminescence as a tool in stratigraphy and 

 in age determination. These researches on thermoluminescence for the past de- 

 cade at the University of Wisconsin have been made possible by support from 

 the Atomic Energy Commission. 



BIBLIOGRAPHY 



Bergstrom, R. E„ 1956, Surface correlation of some Pennsylvanian limestones of the Mid- 

 Continent by thermoluminescence: Am. Assoc. Petroleum Geologists Bull., v. 40, p. 918. 



Daniels, F., Boyd, C. A., and Saunders, D. F., 1953, Thermoluminescence as a research tool: 

 Science, v. 117, p. 343. 



, and Saunders, D. F., 1951, The thermoluminescence of crystals: Final Rept. 



to U. S. Atomic Energy Comm., Contract AT (11-1) -27. 



Hecklesberg, L. F., and Daniels, F., 1957, The thermoluminescence of fourteen alkali 

 halides: Jour. Phys. Chemistry, v. 61, p. 414-418. 



Kurath, S. F., 1957, Storage of energy in metamict minerals: Am. Mineralogist, v. 42, p. 91. 



Lewis, D. R., 1956, The thermoluminescence of dolomite and calcite: Jour. Phys. Chemistry, 

 v. 60, p. 698-701. 



Moore, L., 1957, Thermoluminescence of sulfates: Jour. Phys. Chemistry, v. 61, p. 636-640. 



Morehead, F. F., and Daniels, F., 1952, Storage of radiation energy in crystalline lithium 

 fluoride and metamict minerals: Jour. Phys. Chemistry, v. 56, p. 546. 



Ockermann, J. B., and Daniels, F., 1954, Alpha-radioactivity of some rocks and common 

 materials: Jour. Phys. Chemistry, v. 58, p. 926. 



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