Form Approved
REPORT DOCUMENTATION PAGE
OMB No. 0704-0188
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1. AGENCY USE ONLY (Leave blank)
2. REPORT DATE
3. REPORT TYPE AND DATES COVERED
April 1995
4. TITLE AND SUBTITLE
5. FUNDING NUMBERS
Permafrost Formation Time
PR: 4A161102AT24
TA: BS/0045
6. AUTHORS
Virgil J. Lunardini
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)
8. PERFORMING ORGANIZATION
REPORT NUMBER
U.S. Army Cold Regions Research and Engineering Laboratory
72 Lyme Road
CRREL Report 95-8
Hanover, New Hampshire 03755-1290
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)
10. SPONSORING/MONITORING
AGENCY REPORT NUMBER
Office of the Chief of Engineers
Washington, DC 20314-1000
11. SUPPLEMENTARY NOTES
Funding also provided by U.S. Army Strategic Environmental Research and Development Program 2.6.00 78 203
12a. DISTRIBUTION/AVAILABILITY STATEMENT
12b. DISTRIBUTION CODE
Approved for public release; distribution is unlimited.
Available from NTIS, Springfield, Virginia 22161.
13. ABSTRACT (Maximum 200 words)
The age of permafrost is closely linked to the time required for soil systems to freeze, since the permafrost must be at least
as old as the formation time. Cycles of freezethaw will complicate the relation between the freeze rate and the age. A
model based on pure conduction heat transfer with freezethaw is used to predict the time required for a given thickness of
permafrost to develop, either heterogenetically or syngenetically. The formation time is a function of the long-term geo-
thermal gradient (initial temperature of the thawed soil), the ratios of the frozen to thawed thermal properties, and the tem-
perature history of the upper surface of the permafrost (higher than the air temperature). The simple theory allows universal
graphs to be produced that predict the formation time for a given thickness of permafrost. Realistic soil property ratios and
paleotemperature scenarios will then lead to estimates of the formation time of permafrost for a specific site. The model in-
dicates that deep permafrost (more than 1500 m) requires formation times on the order of the complete Quaternary Period.
14. SUBJECT TERMS
15. NUMBER OF PAGES
48
Age of permafrost
Permafrost
16. PRICE CODE
Paleotemperatures
Permafrost growth and melt
17. SECURITY CLASSIFICATION
18. SECURITY CLASSIFICATION
19. SECURITY CLASSIFICATION
20. LIMITATION OF ABSTRACT
OF REPORT
OF THIS PAGE
OF ABSTRACT
UNCLASSIFIED
UNCLASSIFIED
UNCLASSIFIED
Standard Form 298 (Rev. 2-89)
NSN 7540-01-280-5500
Prescribed by ANSI Std. Z39-18
298-102
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