scholarly journals Recent Glacial History of an Alpine Area in the Colorado Front Range, U.S.A.: I. Establishing a Lichen-Growth Curve

1967 ◽  
Vol 6 (48) ◽  
pp. 817-832 ◽  
Author(s):  
James B. Benedict
Keyword(s):  
Growth Curve ◽  
Average Rate ◽  
Colorado Front Range ◽  
Ground Moraine ◽  
Front Range ◽  
Exposure Age ◽  
Rhizocarpon Geographicum ◽  
Valley Glacier ◽  
History Of ◽  
Lichen Growth

A lichen-growth curve has been developed for dating Recent glacial and periglacial deposits in the Indian Peaks area of the Colorado Front Range.Rhizocarpon geographicumwas selected for the study because of its long life span and consistent size-age relationship. The species grows at different rates in different micro-environments, with moisture, stability of substrate and length of snow-free growing season having the greatest effect. Growth rates were determined indirectly, by measuring the maximum diameters of circular or nearly circular thalli growing on surfaces of known exposure age. Measurements were made on 24 historically dated surfaces, ranging in age from 25 to 69 yr., and on three radiocarbon-dated surfaces, including (1) mudflow levees younger than 180 yr., (2) a rock wall built by prehistoric Indians about 970 yr. ago, and (3) ground moraine deposited by a retreating valley glacier about 2,460 radiocarbon years ago.R. geographicurrzgrows very rapidly (14. mm./100 yr.) during the First 100 yr. of its life. Growth then slows to an average rate of 3.3 mm./100 yr. The completed growth curve is believed to be suitable for dating deposits at least as old as 3,000 yr.

scholarly journals Recent Glacial History of an Alpine Area in the Colorado Front Range, U.S.A.: I. Establishing a Lichen-Growth Curve

1967 ◽  
Vol 6 (48) ◽  
pp. 817-832 ◽  
Author(s):  
James B. Benedict
Keyword(s):  
Growth Curve ◽  
Average Rate ◽  
Colorado Front Range ◽  
Ground Moraine ◽  
Front Range ◽  
Exposure Age ◽  
Rhizocarpon Geographicum ◽  
Valley Glacier ◽  
History Of ◽  
Lichen Growth

A lichen-growth curve has been developed for dating Recent glacial and periglacial deposits in the Indian Peaks area of the Colorado Front Range. Rhizocarpon geographicum was selected for the study because of its long life span and consistent size-age relationship. The species grows at different rates in different micro-environments, with moisture, stability of substrate and length of snow-free growing season having the greatest effect. Growth rates were determined indirectly, by measuring the maximum diameters of circular or nearly circular thalli growing on surfaces of known exposure age. Measurements were made on 24 historically dated surfaces, ranging in age from 25 to 69 yr., and on three radiocarbon-dated surfaces, including (1) mudflow levees younger than 180 yr., (2) a rock wall built by prehistoric Indians about 970 yr. ago, and (3) ground moraine deposited by a retreating valley glacier about 2,460 radiocarbon years ago. R. geographicurrz grows very rapidly (14. mm./100 yr.) during the First 100 yr. of its life. Growth then slows to an average rate of 3.3 mm./100 yr. The completed growth curve is believed to be suitable for dating deposits at least as old as 3,000 yr.

scholarly journals Recent Glacial History of an Alpine Area in the Colorado Front Range, U.S.A.: II. Dating the Glacial Deposits

1968 ◽  
Vol 7 (49) ◽  
pp. 77-87 ◽  
Author(s):  
James B. Benedict
Keyword(s):  
Local Development ◽  
Colorado Front Range ◽  
Front Range ◽  
Glacial History ◽  
Glacial Deposits ◽  
Radiocarbon Dates ◽  
The Past ◽  
Rhizocarpon Geographicum ◽  
History Of ◽  
Mountain Glaciation

AbstractRecent glacial deposits in the Indian Peaks area of the Colorado Front Range have been dated lichenometricaily, using a growth curve developed locally forRhizocarpon geographicum. Radiocarbon dates, where available, tend to support the lichen chronology. Three distinct intervals of glaciation, each consisting of several minor pulsations, have occurred in the area during the past 4500 years. The earliest advance (Temple Lake Stade) is dated at 2500–700 b.c. A later advance (Arikaree Stade) began in about a.d. 100 and ended in a.d. 1000. The most recent advance (Gannett Peak Stade) is dated at a.d. 1650–1850. It remains to be seen whether the Arikaree Stade was purely a local development or whether glaciers were advancing elsewhere in the cordilleran region during this interval. Alluviation on the plains east of the Colorado Front Range seems to have occurred during the waning stages of mountain glaciation.

scholarly journals Recent Glacial History of an Alpine Area in the Colorado Front Range, U.S.A.: II. Dating the Glacial Deposits

1968 ◽  
Vol 7 (49) ◽  
pp. 77-87 ◽  
Author(s):  
James B. Benedict
Keyword(s):  
Local Development ◽  
Colorado Front Range ◽  
Front Range ◽  
Glacial History ◽  
Glacial Deposits ◽  
Radiocarbon Dates ◽  
The Past ◽  
Rhizocarpon Geographicum ◽  
History Of ◽  
Mountain Glaciation

AbstractRecent glacial deposits in the Indian Peaks area of the Colorado Front Range have been dated lichenometricaily, using a growth curve developed locally for Rhizocarpon geographicum. Radiocarbon dates, where available, tend to support the lichen chronology. Three distinct intervals of glaciation, each consisting of several minor pulsations, have occurred in the area during the past 4500 years. The earliest advance (Temple Lake Stade) is dated at 2500–700 b.c. A later advance (Arikaree Stade) began in about a.d. 100 and ended in a.d. 1000. The most recent advance (Gannett Peak Stade) is dated at a.d. 1650–1850. It remains to be seen whether the Arikaree Stade was purely a local development or whether glaciers were advancing elsewhere in the cordilleran region during this interval. Alluviation on the plains east of the Colorado Front Range seems to have occurred during the waning stages of mountain glaciation.

scholarly journals Short Notes: Note on the “Arikaree Stade” of the Rocky Mountains Neoglacial

1971 ◽  
Vol 10 (58) ◽  
pp. 143-144 ◽  
Author(s):  
William Mahaney
Keyword(s):  
Growth Rate ◽  
Rocky Mountains ◽  
Colorado Front Range ◽  
Rate Curve ◽  
Front Range ◽  
Rhizocarpon Geographicum ◽  
Alternative Type ◽  
The Temple

AbstractNeoglacial deposits in the Indian Peaks section of the Colorado Front Range have been dated lichenometrically by recourse to a growth-rate curve developed forRhizocarpon geographicumand three glacial fluctuations of the Temple Lake (4500–2700B.P.), “Arikaree” (1900–1000B.P.) and Gannett Peak (300–50B.P.) have been recognized and identified by Benedict (1968). Recent soil investigations on neoglacial deposits suggest the need to define an alternative type “Arikaree” in the Indian Peaks.

scholarly journals Short Notes: Note on the “Arikaree Stade” of the Rocky Mountains Neoglacial

1971 ◽  
Vol 10 (58) ◽  
pp. 143-144
Author(s):  
William Mahaney
Keyword(s):  
Growth Rate ◽  
Rocky Mountains ◽  
Colorado Front Range ◽  
Rate Curve ◽  
Front Range ◽  
Rhizocarpon Geographicum ◽  
Alternative Type ◽  
The Temple

AbstractNeoglacial deposits in the Indian Peaks section of the Colorado Front Range have been dated lichenometrically by recourse to a growth-rate curve developed for Rhizocarpon geographicum and three glacial fluctuations of the Temple Lake (4500–2700 B.P. ), “Arikaree” (1900–1000 B.P.) and Gannett Peak (300–50 B.P.) have been recognized and identified by Benedict (1968). Recent soil investigations on neoglacial deposits suggest the need to define an alternative type “Arikaree” in the Indian Peaks.

scholarly journals Holocene Glacier Fluctuations in the Torngat Mountains, Northern Labrador

2007 ◽  
Vol 37 (2) ◽  
pp. 211-216 ◽  
Author(s):  
William D. McCoy
Keyword(s):  
Growth Curve ◽  
Local Area ◽  
Baffin Island ◽  
Relative Age ◽  
Glacier Fluctuations ◽  
Glacier Recession ◽  
Rhizocarpon Geographicum ◽  
Lichen Growth

ABSTRACT Lichen measurements and other relative-age data were collected from deposits of several cirque glaciers in the Torngat Mountains of northern Labrador. Lichen growth stations were established, but no lichen-growth curve has yet been determined for the local area. However, moraines can be correlated between valleys on the basis of the largest diameter thallus of Rhizocarpon geographicum sensu lato combined with other relative-age data. These data suggest several discrete periods of Holocene glacier recession. If the R. geographicum s. I. growth curve established for the northern Cumberland Peninsula of Baffin Island (MILLER, 1975) is valid for similar environments in the Torngat Mountains, then glacier recession occurred < 150, 400, 550-750, 950, ≥ 1850, > 1850, ≥ 2800, > 2800, ≥ 4000, and > > 4000 yr BP. The latest three periods of glacier recession may correlate with periods of glacier recession on the Cumberland Peninsula of Baffin Island.

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