Work by Thouret and others (1996) examined glacial stades in the Ruiz-Tolima massif and possibly equivalent stades in other glacierized areas (table 1). Thouret and others (1996) noted that the late neoglacial stade (approximately 1600's to 1900's), named the "Little Ice Age," is well documented on the basis of terminal moraines near present glacier termini. Evidence for earlier neoglacial stades is more problematical (Thouret and others, 1992, 1996).
Table 1.-- Estimate of the glaciated areas in the Colombian and Ecuadorean Andes during the last ("Fuquene") glaciation[Modified from Thouret and others, 1996. Abbreviations: yrs B.P., years before present; ca., circa; MIS, marine isotope stage]
|
|
|
Approximate extent of glacierized areas (square kilometers) |
|
|
||||||
|---|---|---|---|---|---|---|---|---|---|---|
|
|
|
Massif |
Total area |
|
|
|||||
|
Glacial stade number |
Age |
Nevado del Ruiz, Nevado del Tolima1 |
Sierra Nevada del Cocuy1 |
Sierra Nevada de Santa Marta1 |
Nevada del Huila |
Colombian Andes2 |
Ecuadorean Andes2 |
Eastern Africa2 |
Average elevation of ice fronts Ruiz-Tolima (meters above mean sea level) |
Average elevation of valley glacier fronts Ruiz-Tolima |
|
|
Present |
34-36 |
28-30 |
14-18 |
25-28 |
100-112 |
220 |
9.5 |
4,750-4,700 |
4,500-4,400 |
|
1b |
Late neoglacial, late Holocene (?) |
Inner Ruiz |
150 |
107 |
30(?) |
350-400 |
255 |
31 |
4,600-4,300 |
4,300-4,200 |
|
1a |
Early neoglacial, late Holocene (?) |
Outer |
Corralitos |
Bolívar |
|
|
|
|
|
|
|
2b |
Late Santa Isabel- early Holocene [ca. 6,200 (?)] |
|
|
|
|
|
|
|
4,300-4,150 |
4,300-4,200 |
|
2a |
Early Santa Isabel (7,400- 7,200) |
|
|
|
|
|
|
|
|
4,200-4,100 |
|
3b |
Late Otun, late late-glacial (ca. 11,000- 10,000) |
|
Bocatoma |
Naboba |
|
2,600 |
460 |
190 |
4,000-3,800 |
3,800-3,600 |
|
3a |
Early Otun, early late-glacial (MIS 2; ca. 13,000- 12,400) |
800 |
1,000 |
850 |
250(?) |
3,500 |
2,050 |
|
3,800-3,600 |
3,400-3,300 |
|
4b |
Late Murillo- late late full-glacial (ca. 18,000- 14,000) |
|
Early Lagunilla |
Mamancanaca |
|
|
|
|
3,600-3,400 |
3,300-3,100 |
|
4a |
Early Murillo- early late full-glacial (MIS 3-2; ca. 27,000- 24,000) |
1,500(?) |
2,000(?) |
1,500(?) |
(?) |
12,000- |
(?) |
800 |
3,400-3,300 |
3,300-3,100 |
|
5b |
Late "Río Recio" early to middle full-glacial (MIS 3; ca. 40,000?) |
|
Río Negro |
|
|
|
|
|
3,300-3,200 |
3,100-2,900 |
|
5a |
Early "Río Recio" early full-glacial or early glacial(?) (MIS 4; >53,000?) |
|
|
|
|
|
|
|
3,300-3,200 |
3,100-2,900 |
1 Glacial stades in the Ruiz-Tolima massif are given along with possible equivalents in the Sierra Nevada del Cocuy (Van der Hammen and others, 1980/81) and the Sierra Nevada de Santa Marta (Raasveldt, 1957; Van der Hammen, 1984).
2 Compare the total glacierized area in the Colombian Andes with that in the Ecuadorean Andes (Hastenrath, 1981) and eastern Africa (Hastenrath, 1984). During the full-glacial period, the glaciers of the Colombian and Ecuadorean Andes were probably the most extensive ice fields among the equatorial high-mountains.
Herd (1973) estimated the extension of the Ruiz-Tolima glaciers to have been 100 km2 during the "Little Ice Age," and Raasveldt (1957) calculated the extent of the last ice advance during the Bolívar stade to have covered 105 km2 on the Sierra Nevada de Santa Marta.
Four different areas in Colombia are glacierized at the present: the Sierra Nevada de Santa Marta, the Sierra Nevada del Cocuy (Cordillera Oriental), the Ruiz-Tolima massif (Cordillera Central), and the Nevado del Huila (Cordillera Central). Glaciers in the Sierra Nevada de Santa Marta and in the Sierra Nevada del Cocuy are classified as either mountain or alpine; the Ruiz-Tolima massif and Nevado del Huila are large stratovolcanoes that have shieldlike summit ice caps and a few outlet glaciers.
Various figures have been given for the total extent of glacierized areas in recent years. The variation depends on the technique of measurement and the date of the source materials. Work by Jordan and others (1989) gave the total number of glaciers at 246 or 247 on 9 mountains, with a total area of approximately 109 km2. His work was based on fieldwork and aerial photography dating from 1957 to 1978 (table 2). This author has measured the extent of ice-and-snow areas on Landsat 1-3 multispectral scanner (MSS) images from the early 1970's and determined a total area of 104 km2 (see table 3). Although the Landsat imagery does not supply the spatial resolution of vertical aerial photography, it offers the opportunity to look at all the glaciers at the same time by the use of a uniform method. Thouret and others (1996) gave a range from 100 to 112 km2 for the presently glacierized areas of Colombia.
Table 2.-- Glaciers of Colombia
[Modified from Jordan and others, 1989]
|
Area |
Flight years of plotted aerial photographs |
Number of glaciers |
Position (lat-long) |
Size of total glacier area (square kilometers) |
||
|---|---|---|---|---|---|---|
|
Sierra Nevada de Santa Marta |
1957, 1974 |
|
88 |
|
10°34'N., 73°43'W. |
16.26 |
|
Sierra Nevada del Cocuy |
1959, 1978 |
|
88 |
|
06°27'N., 72°18'W. |
39.12 |
|
Ruiz |
|
|
15 |
(16) |
|
21.4 |
|
El Cisne |
|
|
4 |
|
|
.11 |
|
Santa Isabel |
|
|
16 |
|
|
9.78 |
|
Quindio |
|
|
7 |
|
|
.44 |
|
Tolima |
|
|
11 |
|
|
2.22 |
|
Parque Nacional de los Nevados |
1959 |
Subtotal |
53 |
(54) |
04°50'N., 75°20'W. |
33.95 |
|
Nevado del Huila |
1965 |
|
17 |
|
02°55'N., 76°05'W. |
19.77 |
|
|
|
Total |
246 |
(247) |
|
108.49 |
Table 3.-- Glaciers and snowfields of Colombia measured from Landsat images
|
Glacierized area |
Date of image |
Size (square kilometers) |
|---|---|---|
|
Sierra Nevada de Santa Marta |
01 Jan 73 |
14.1 |
|
Sierra Nevada del Cocuy |
18 Jan 73 |
28.0 |
|
Ruiz-Tolima massif (Parque Nacional de los Nevados) |
01 Feb 76 |
|
|
Ruiz |
|
21.3 |
|
Santa Isabel |
|
10.8 |
|
Tolima |
|
3.8 |
|
Nevado del Huila |
01 Feb 76 |
26.0 |
|
|
|
|
|
|
Total |
104.0 |
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U.S. Geological Survey, U.S.Department of the Interior