Glacier Maps of the Sierra Nevada de Mérida, Venezuela

Transcripción

Braun, C., The Disappearance of Glaciers in Venezuela
Map Compilation
Glacier Maps of the Sierra Nevada de Mérida, Venezuela
Map 1
Map 2
Source
Jahn (1925)
Map 4
Blumenthal
(1923)
Gunther
(1940, 1941a)
Gunther (1940)
Map 5
Busk (1964)
Map 6
Schubert (1972)
Map 7
Schubert (1972)
Map 8
Schubert (1992)
Map 9, 10
Schubert (1998)
Map 11
Mahaney et al.
(2000)
Mahaney et al.
(2009)
Mahaney et al.
(2009)
National Park
Map (1:50,000)
Topographic Map
NC 19-13
Topographic Map
HOJA 5941
Topographic Map
HOJA 6041
Map 3
Map 12
Map 13
Map 14
Map 15
Map 16
Map 17
mapcompilation
Description
Map showing glacier cover, glacier names, summit names, and
summit elevations in the Sierra Nevada de Mérida in 1910/1911.
Simple sketch map of the Sierra Nevada de Mérida intended as a
guide for hiking and mountain climbing.
Gunther’s map of the Sierra Nevada de Mérida is based on Jahn
(1925) and Gunther’s own observations in 1939 and 1940.
Highly-generalized sketch map of the glaciers in the Pico
Bolivar Massif, useful as an orientation map for climbers.
Simple sketch map of the Sierra Nevada de Mérida intended as a
guide for hiking, climbing, and trout fishing.
Detailed glacial-geomorphic and topographic map of the Pico
Bolivar Massif (Schubert, 1972, Fig. 1).
Simple sketch map comparing glacier extent in 1910/1911 and
1972 in the Pico Bolivar Massif (Schubert, 1972, Fig. 5).
Map comparing glacier extent in the Sierra Nevada de Mérida in
1910/1911 and 1952 as determined from aerial photographs.
Schubert’s 1998 maps are generalizations of his 1992 map based
on aerial photographs from 1952.
Generalized sketch map based on the available national park
hiking map for the Sierra Nevada de Mérida.
Annotated 1952 aerial photograph map of the Pico
Humboldt/Pico Bonpland Massif.
Sketch map of the Pico Humboldt foreland. The glacier margin
was presumably estimated from the 1952 aerial photographs.
Map of the Sierra Nevada de Mérida and surrounding area
showing hiking trails and generalized topography.
Official topographic map NC 19-13 Merida (1:250,000, contour
interval 40 m) produced in 1978.
Official topographic map HOJA 5941 (1:100,000, contour
Official topographic map HOJA 6041 (1:100,000, contour
Page 1
Map Compilation
Map 1 (Jahn, 1925)
Microfilm scan of Jahn’s original map depicting glacier cover in the Sierra Nevada de Mérida (Jahn,
1925) in 1910/1911 (scale 1:100,000). This remained effectively the only map showing approximate
glacier extents in Venezuela until the mapping efforts by Schubert (1972, 1992, 1998).
Alfredo Jahn (1867 to 1940) was a civil engineer, surveyor, botanist, geographer, avid mountaineer, and
prolific map maker (for example Lake Valencia, cf. Crist and and Chardon, 1941, their Fig. 2) and
recorded the first ascent of Pico Humboldt on 16 January 1911 via the Sievers Glacier. Jahn also
conducted some of the first official elevation determinations in the Sierra Nevada de Mérida (e.g. Jahn,
1907) and was responsible for lake level measurements in Lake Valencia between 1905 and 1938 (Crist
and Chardon, 1941; Gschwendtner, 1963).
Blumenthal (1923, Page 221) considered this map the ‘baptism’ of the Sierra Nevada de Mérida as it
provided, for the first time, the names and elevations of the mountains. It is important to note that the
names used for most glaciers and certain lakes in the Sierra Nevada de Mérida are somewhat inconsistent
and have changed over time, making it sometimes difficult to compare the work from different authors
(cf. Federici and Pappalardo, 2010).
mapcompilation
Page 2
Map Compilation
Jahn (1925) mapped the entire Pico Espejo summit and ridge area as covered by the Espejo Glacier that
extended westward into the Laguna Espejo valley/cirque to an elevation of about 4,500 m asl (Schubert,
1992). This matches approximately the glacier extent depicted in the Goering painting created between
1864 and 1874 (cf. Schubert, 1984, Fig. 4).
Jahn named many of the glaciers in the Sierra Nevada de Mérida in honor of previous explorers
(Schubert, 1992). Schubert (1972, 1992, 1998), unfortunately, re-named many of the glaciers in the Sierra
Nevada de Mérida using the local geographic names of the valleys they occupied during the Last Glacial
Maximum, creating some confusion and inconsistencies in the literature.


Schubert (1972) separated what Jahn mapped as the Burgoin Glacier into the West and North
Glacier to designate their approximate aspects. The West Glacier faces more-or-less due west and
would extend into the Laguna Espejo cirque. The North Glacier faces northwest and would
extend into an adjacent cirque and valley.
Schubert (1992, 1998) reintroduced the ‘new’ Espejo Glacier, matching approximately Jahn’s
Burgoin Glacier and Schubert’s own West and North Glacier (Schubert, 1972).
mapcompilation
Page 3
Map Compilation
Map 2: Blumenthal (1923)
mapcompilation
Page 4
Map Compilation
Blumenthal (1923) included this simple sketch map of the Sierra Nevada de Mérida based on his travels
in 1922. The map was clearly not intended to accurately depict the shapes of glacier, but rather to serve as
a guide for hiking and climbing.
This map was deemed highly inaccurate by Gunther (1940). Blumenthal was engaged in geologic
mapping for petroleum exploration and thus presumably a competent cartographer. Some of the perceived
inaccuracies may therefore reflect glacier recession between Blumenthal’s visit in 1922 and Gunther’s
expeditions in 1939 and 1940.
mapcompilation
Page 5
Map Compilation
Map 3 (Gunther, 1940, 1941a)
mapcompilation
Page 6
Map Compilation
Gunther’s map (Gunther, 1940, 1941a) depicts glacier extent in the Sierra Nevada de Mérida after Jahn
(1925) and supplemented by Gunther’s own observations and measurements during two climbing
expeditions in 1939 and 1940 (Gunther 1940, 1941a, b). Gunther used the same glacier names as Jahn
(1925) and it is interesting to compare both maps.
Gunther mapped the Espejo Glacier considerably smaller than Jahn as essentially limited to the western
side of the Pico Espejo summit ridge area (cf. Map 1) and not extending too far towards Laguna Espejo.
This subtle difference is consistent with the well-documented asymmetry in glacier cover and glacier
recession in the early part of the 20th century in the Sierra Nevada de Mérida (cf. Sievers, 1908;
Blumenthal, 1923; Schubert, 1992).
The map also shows how the names used for certain lakes have changed:
Laguna Verde  Laguna El Suero

Laguna Verde as mapped and described by Jahn (1925), Gunther (1940, 1941a, b), and HanburyTracy (1944) is today called Laguna El Suero. However, the name Laguna Verde may have been
quite reasonable at the time when the Laguna Verde Glacier (today: Humboldt Glacier) extended
much closer towards the lake and glacial meltwater/sediment inflow may have caused the lake to
exhibit a greenish color.
Laguna Negra  Laguna Verde

Laguna Negra as mapped and described by Jahn (1925), Gunther (1940, 1941a, b), and HanburyTracy (1944) is today called Laguna Verde, although the old name Laguna Negra seems more
appropriate today as the lake is large, deep, and appears black. The old name Laguna Negra
indicates or perhaps even emphasizes that the lake was not greenish in color (in contrast to
Laguna Verde upstream). This may suggest that the lobe of the Humboldt Glacier descending
towards the lake at the time did not cause sufficient glacial meltwater/sediment input to yield a
greenish color.
mapcompilation
Page 7
Map Compilation
Map 4 (Gunther, 1940)
Highly-generalized close-up map of the glaciers located in the Pico Bolivar Massif based on Gunther’s
observations during a climbing expedition in February 1939 (Gunther, 1940). The sketch map is clearly
not intended for glacier area determinations, but is very useful as an orientation map for climbers and
hikers. The glacier names correspond to Jahn (1925) and Gunther (1941a).
mapcompilation
Page 8
Map Compilation
Map 5 (Busk, 1964)
Busk (1964) prepared this map of the Sierra Nevada de Mérida based on earlier maps by Jahn (1925),
Gunther (1940, 1941a), other unpublished maps, personal observations, and conversations with local
people.
This map was obviously not designed to accurately depict contemporary glacier cover, but rather to serve
as an orientation map for hikers, mountain climbers, and trout fishing. Sir Douglas Busk was the British
Ambassador to Venezuela in the early 1960s and completed a rare winter weekend ascent of Pico Bolivar
with Eric Shipton in 1963 (Band and Peck, 1991).
mapcompilation
Page 9
Map Compilation
Map 6.1 (Schubert, 1972)
Glacial-geomorphic and topographic map of the Pico Bolivar Massif prepared by Schubert (1972, Fig. 1).
Map 6.2 is a close-up of the glaciers around Pico Bolivar.
mapcompilation
Page 10
Map Compilation
Map 6.2 (Schubert, 1972)
Glacial-geomorphic and topographic map of the Pico Bolivar summit and surrounding area prepared by
Schubert (1972, Fig. 1). With this map Schubert introduced three new glacier names: West Glacier, North
Glacier, and East Glacier.



The Espejo Glacier as mapped by Jahn and Gunther obviously did not exist anymore in 1972
when Schubert was mapping around Pico Bolivar.
Schubert separated what Jahn and Gunther mapped as the Bourgoin Glacier into the West and
North Glacier to designate their approximate orientation. The West Glacier faces westward and
would extend into the Laguna Espejo valley/cirque. The North Glacier faces northwest and would
extend into the adjacent cirque and valley.
The East Glacier was previously mapped as Karsten Glacier by Jahn and Gunther.
The name Las Hermanas Glacier used on this map is also confusing. Schubert (1972) used it for the small
eastern lobe of the Timoncito Glacier. Jahn, Blumenthal, and Gunther, however, mapped the Hermanas
Glacier as a small separate and glacier from the Timoncito Glacier located a few km further to the east
(cf. Map 4).
However, these new names used by Schubert (1972) were revised again by Schubert (1992, 1998) when
he introduced a series of new names for many of the glaciers in the Sierra Nevada de Mérida.
mapcompilation
Page 11
Map Compilation
Map 7 (Schubert, 1972, Fig. 5)
Schubert’s 1972 map compared glacier cover in the Pico Bolivar / Pico La Concha Massifs between 1910
and 1972. This map is obviously too generalized for quantitative analysis, but allows useful qualitative
comparisons:



Pico El Toro was glacier-covered in 1910, but not anymore in 1972. This is consistent with other
evidence (e.g. Blumenthal, 1923; Schubert, 1992). In 1868 reports indicated an ice thickness of
between 8 and 16 m on the flanks of Pico El Toro. By 1890 deglaciation was on the way and rock
patches were emerging from below the ice. By 1915 only a small remnant remained and by 1931
Pico El Toro was ice-free (after Schubert, 1992, Page 60).
The Garza Glacier on the western side of Pico La Concha apparently still existed in 1972,
whereas the Mucuy Glacier on the eastern side had already disappeared. Both glaciers existed in
1952 (Schubert, 1992, 1998). This makes sense in terms of their relative orientation and size. The
Garza Glacier was larger than the Mucuy Glacier in 1910/11 (Jahn, 1925, Gunther, 1940, 1941a)
and was located on the western side, protected from solar radiation by the diurnal cycle in cloud
cover (cf. Flohn, 1968). The Garza Glacier had disappeared by 1991 (Schubert, 1998).
The basic configuration of the four glaciers around Pico Bolivar in February 1972 was the same
as on Schubert’s detailed 1952 aerial photograph map (Schubert, 1992).
mapcompilation
Page 12
Map Compilation
Map 8 (Schubert, 1992)
Glacier distribution in the Sierra Nevada de Mérida in 1910/1911 (after Jahn, 1925) and in 1952 as
mapped by Schubert (1992) from aerial photographs. Glacier-covered area in 1910 was about 10 km2 and
about 2.91 km2 in 1952 (Schubert, 1992, 1998).
The table below lists glacier names and area for individual glaciers (after Schubert, 1992, Table 1).
Massif
Pico Bolivar
Schubert (1992)
1) Espejo Glacier
2) Timoncito Glacier
3) El Encierro Glacier
4) El Encierro Glacier
Pico La Concha 1) Ño León Glacier
2) Coromoto Glacier W-Remnant
Pico Humboldt (1, 2) Coromoto Glacier
Pico Bonpland E-Remnant
3) Siniguis Glacier
4) Nuestra Señora Glacier
mapcompilation
Jahn (1925)
Area (km2)
Espejo Glacier
0.27
Timoncito/Hermanas Glacier
0.17
Bourgoin Glacier
0.17
Karsten Glacier
0.10
Garza Glacier
0.10
Mucuy Glacier
0.07
Laguna Verde Glacier
Codazzi Glacier
2.03
Sievers Glacier
Plazuela Glacier
Page 13
Map Compilation
Note that the summit of Pico Bonpland is marked incorrectly on this map. The actual summit location is
about 1.5 km further to the southwest on the ridge extending northwest towards Pico La Concha (i.e.
separating Glacier #3 and #4).
Unfortunately, Schubert (1992) decided to rename and redefine many of the glaciers in the Sierra Nevada
de Mérida from the original names used by Jahn (1925) and Gunther (1940, 1941a). In addition,
Schubert’s map and associated table contain several errors and inconsistencies. First, Schubert’s ‘new’
Espejo Glacier is not what Jahn and Gunther had mapped as the ‘original’ Espejo Glacier, but rather what
they mapped as the Bourgoin and Espejo Glacier. Second, Glacier #3 was mapped by Jahn and Gunther
as the Karsten Glacier, not as the Bourgoin Glacier. Finally, Glacier #4 was mapped in combination with
Glacier #3 by Jahn and Gunther as the Karsten Glacier (western and eastern section).
Pico Bolivar Massif
 Schubert (1992) reintroduced the ‘new’ Espejo Glacier matching approximately what Jahn and
Gunther mapped as the Bourgoin and Espejo Glacier and what Schubert (1972) mapped as the
West and North Glacier (Schubert, 1972). The original Espejo Glacier covering the Pico Espejo
summit and ridge area had disappeared by 1956. The remnants of the ‘new’ Espejo Glacier or
‘old’ North Glacier are today still visible from downtown Mérida as two small ice/firn patches.
 Jahn (1925) and Schubert (1972) distinguished between the Timoncito Glacier and its easterly
neighbor the Hermanas Glacier, whereas Schubert (1992) combined them. The original Hermanas
Glacier (cf. Map 4) as mapped by Jahn, Blumenthal, and Gunther had more-or-less disappeared
by 1952 and Schubert (1972) introduced the name Las Hermanas Glacier for what was essentially
the smaller eastern lobe of the Timoncito Glacier.
 Schubert (1992) changed the name of the western section of the Karsten Glacier to El Encierro
Glacier in reference to Laguna Del Encierro and associated stream.
 Schubert (1992) introduced the name El Encierro Glacier for the small glacier east of the (other)
El Encierro Glacier. In the past, the El Encierro Glacier was mapped as the Karsten Glacier and
consisted of a western section on the north side of Col Bourgoin and a smaller eastern section
(mapped but unnamed on the map by Schubert, 1972) below and east of La Columna South Peak
towards Pico La Concha.
Pico La Concha Massif
 Schubert (1992) introduced the name Ño León Glacier for what Jahn and Gunther mapped as the
Garza Glacier.
 Schubert (1992) introduced the name Coromoto Glacier W-Remnant for what Jahn and Gunther
mapped as the Mucuy Glacier.
Pico Humboldt and Pico Bonpland Massif
 Schubert (1992) introduced the name Siniguis Glacier for what Jahn and Gunther mapped as the
Sievers Glacier on the southeastern side of Pico Humboldt (= the route Jahn used for his first
ascent of Pico Humboldt on 16 January 1911).
 Schubert (1992) introduced the name Coromoto Glacier E-Remnant to combine what Jahn
mapped separately as the Laguna Verde Glacier and Codazzi Glacier. The name Laguna Verde
Glacier makes sense as it extends towards Laguna Verde, which is today called Laguna El Suero.
Gunther, on the other hand, did not explicitly label the Laguna Verde Glacier on his map but used
the name Humboldt Glacier in his papers for what Jahn mapped as the Laguna Verde Glacier.
The Humboldt Glacier today is the remnant of the Laguna Verde Glacier as mapped by Jahn or
the Humboldt Glacier as described by Gunther and Hanbury-Tracy.
 Schubert (1992) introduced the name Nuestra Señora Glacier for the glacier mapped by Jahn and
Gunther as Plazuela Glacier on the southwestern side of Pico Bonpland.
mapcompilation
Page 14
Map Compilation
Schubert’s 1998 map is a reproduction and generalization of his more detailed map from 1992. The
accompanying table list glacier names, glacier area (in 1952), and glacier appearance in January 1991 for
individual glaciers (cf. Map 10).
mapcompilation
Page 15
Map Compilation
This map included in Schubert (1998) depicts the distribution of glaciers in the Sierra Nevada de Mérida
in 1952 based on aerial photographs. The accompanying table further lists glacier names, glacier area (in
1952), and subjective glacier appearance in January 1991 based on fieldwork and ground photographs. In
the case of the Coromoto Glacier East Remnant, Schubert used a Landsat 2 satellite image from 29
January 1976.
Unfortunately, Schubert changed the glacier numbering system with respect to his 1992 map (Schubert,
1992). In addition, many glacier names have changed over the last 100 years (cf. Map 8) and there are
some inconsistencies in the literature regarding the precise spatial meaning of some glacier names.
Note that the summit of Pico Bonpland is again marked incorrectly on this map. The actual summit
location is about 1.5 km further to the southwest on the ridge extending towards Pico La Concha (i.e.
separating Glacier #9 and #10).
Glacier Appearance in January 1991 (after Schubert, 1998, Table 1)
Glacier Name
Espejo Gl. (1)
Timoncito Gl. (2)
El Encierro Gl. (3)
El Encierro Gl. (4)
Ño León Gl. (5)
Coromoto Gl. West Remnant (6)
Coromoto Gl. East Remnant (7, 8)
Siniguis Gl. (9)
Nuestra Señora Gl. (10)
mapcompilation
Appearance in 1991
Melted into 2 small firn patches
Almost completely disappeared
Lost at least 50 percent of its area
Retreated
Completely disappeared
Retreated
Retreated
Page 16




Map Compilation
The two small ice/firn patches – remnants of the ‘new’ Espejo Glacier (Schubert, 1992) or the
‘old’ North Glacier as mapped by Schubert (1972) – are still visible from the cable car line and
downtown Mérida, but not from the summit of Pico Espejo.
The two El Encierro Glaciers mapped by Schubert (1992, 1998) used to be known as the Karsten
Glacier (western and eastern section) as mapped by Jahn and Gunther.
The two glaciers in the Pico La Concha Massif existed in 1952 and had both disappeared by
1991. Glacier #5 still existed in 1972 (Schubert, 1972).
See comments for Map 8 in reference to the glaciers in the Pico Humboldt/Pico Bonpland Massif.
mapcompilation
Page 17
Map Compilation
Map 11 (Mahaney et al., 2000)
The glacier outlines and glacier names shown here are based on a map for the Parque Nacional “Sierra
Nevada” Sector Sierra Nevada De Merida Mapa Para Excursionistas (see Map 14). This map included
three new glacier names:



Glacier Este is used here for what Jahn and Gunther mapped as the Codazzi Glacier and Schubert
mapped as the Coromoto Glacier East Remnant.
Glacier de La Corona is used here for what is called today the Humboldt Glacier, Jahn mapped as
the Laguna Verde Glacier, Gunther described as the Humboldt Glacier, and Schubert mapped as
the Coromoto Glacier East Remnant. The name Glacier de La Corona is reasonable as the Pico
Humoldt/Pico Bonpland Massif used to be known as the Corona Group (e.g. Blumenthal, 1923;
Jahn, 1925; Gunther, 1940, 1941a, b).
Glacier La Concha is used here for what Jahn and Gunther mapped as the Garza Glacier and
Schubert mapped as the Ño León Glacier.
Glacier extent and shape shown on this map are grossly inaccurate.
mapcompilation
Page 18
Map Compilation
Annotated 1952 aerial photograph map of the Pico Humboldt/Pico Bonpland Massif.
B = Bonpland Lobe
C = Center Lobe
N = Northern Lobe (= Codazzi Glacier after Jahn and Gunther)
Today (2009/2011) the Northern Lobe (or Codazzi Glacier) has disappeared. The Center and Bonpland
Lobe (of the Humboldt Glacier) have receded considerably.
mapcompilation
Page 19
Map Compilation
Mahaney et al. (2009) included this simple sketch map of the Pico Humboldt foreland. The glacier extent
shown here was presumably approximated from the 1952 aerial photographs (see Map 12).
mapcompilation
Page 20
Map Compilation
Map 14
Section of the map Parque Nacional “Sierra Nevada” Sector Sierra Nevada De Merida Mapa Para
Excursionistas (1:50,000). Glacier extent and shape shown on this map are grossly inaccurate.
mapcompilation
Page 21
Map Compilation
Map 15
Section of topographic map NC 19-13 Merida (1:250,000, contour interval 40 m) produced in 1978 based
on 1:100,000 scale topographic maps from 1964 and 1970. Glacier extent and shape shown on this map
are grossly inaccurate.
mapcompilation
Page 22
Map Compilation
Map 16
Section of topographic map HOJA 5941 (1:100,000, contour interval 40 m) produced in 1977 based on
aerial photography acquired between 1960 and 1973. Glacier extent and shape shown on this map are
grossly inaccurate.
mapcompilation
Page 23
Map Compilation
Map 17
Section of topographic map HOJA 6041 (1:100,000, contour interval 40 m) produced in 1977 based on
aerial photography acquired in 1960. Glacier extent and shape shown on this map are grossly inaccurate.
mapcompilation
Page 24

Glacier Maps of the Sierra Nevada de Mérida, Venezuela

Transcripción

Documentos relacionados

Untitled - Instituto de Geofísica

Author`s personal copy - Instituto de Geofísica

catalogue of excursions from el calafate

TONIgHt: CHICAGO