Santa Cruz Province, Argentina
All photos by Jim Reynolds
|Santa Cruz is the southernmost mainland province in Argentina. It encompasses
all of the environments found throughout Patagonia: a deserted, nearly
pristine, coastline flanked by imposing sea cliffs carved into Neogene
strata. A monotonous, broad, steppe-like pampa developed on elevated marine
terraces between the sea and the mountains. Rugged, imposing peaks of the
Southern Andes rise from the pampas and collect the moisture blown landward
by the westerly winds coming off of the South Pacific Ocean, leaving the
steppes to the east in a state of semi-aridity. Numerous valley glaciers
descend from the Patagonian ice sheet situated at higher elevations in
the mountains. During the last Pleistocene advance, the glaciers deposited
terminal and recessional moraines that dammed the rivers and formed a series
of finger lakes that portrude from the mountains onto the steppes.
The Patagonian coast is hammered by vicious
storms, strong longshore currents, and impressive tides; the mountains
are incessantly scraped by the constant motion of moving masses of ice;
and the steppes are gnawed away by the ever-present wind howling in from
the west on a clear day and driving torrents of rain from the southeast
in foul weather. Such continuous displays of nature's power continue to
discourage people from settling the vast expanses of Patagonia.
||To travel from Tierra del Fuego (on the horizon)
to the mainland (foreground) a ferry carries passengers and vehicles across
the Straits of Magellan at Primera Angostura (First Narrows). Both sides
of the Straits are situated in Chilean Territory.
|Sea lions, or sea wolves, as they are called
locally, are abundant along the Patagonian coast, although they are more
common farther to the north. Once hunted to near-extinction, the Argentine
government placed them under federal protection in the early 20th Century.
Their rebound is one of the great conservation success stories in South
Rookeries of Magellenic Penguins are established
all along the Patagonian coast. A sizeable rookery at Cabo Virgenes, just
across the border north of the Straits of Magellan is visted by everyone
who goes to stand where the Straits enter the South Atlantic Ocean at the
southeasternmost point of the South American continent.
See more penguin photos!
|Horizontal Neogene strata comprise the sea cliff
exposures along most of the Patagonian coastline. Interbedded volcanic
layers are abundant, attesting to the strong westerly winds for which Patagonia
is renowned. In spite of excellent exposure, little has been published
about these strata, probably due to the difficulty of access for long stretches
of the coastline. These beds, just north of Cabo Buentiempo, are typical
of exposures all along the coast.
||Most of the Patagonian coastline is a deserted
beach in front of sea cliffs cut into elevated marine terraces. This beach
is accessible by ranch roads to the east of Estancia Angelina in southern
Santa Cruz province. The Neogene strata exposed in the cliffs have not
been closely studied.
The tidal range in the southern part of the
province is around 6 m, causing the shoreline to recede more than 4 km
near Río Gallegos.
|Laguna San Julián is a well-protected
bay that is rich in history. Magellan and his crews spent their first winter
camped on its shores. Later, Sir Francis Drake anchored here to execute
two mutineers. Charles Darwin commented on the white cliffs seen around
the bay and all along the coast of this part of Patagonia. The French author,
Antoine de Saint-Exupery, flew the first Patagonian air mail flight into
the nearby port of San Julián.
||The constant assault of the waves on the poorly
consolidated strata that make up the cliffs causes rapid retreat of the
shoreline. Three processes combine, however to allow the continent to keep
prograding eastward: 1) post-glacial, isostatic rebound, 2) epeirogenic
uplift related to the Andean Orogeny to the west, and 3) rapid eustatic
changes due to gobal climatic patterns. With each pulse of uplift, sediment
from the eroded sea cliffs and rivers is distributed along the coastline
in a broad subtidal terrace. These sands and muds will comprise the next
marine terraces that rise from the sea. The end result is that most of
the Patagonian pampa is a series of stepped marine terraces that gradually
climb to the Andes on the western side of the continent.
|Large flocks of pale, pink flamingos are seen
in the coastal region and on the lakes and ponds throughout Patagonia.
||The Río Santa Cruz incised a 170 m deep,
broad valley in the rising Patagonian steppes. In the first European exploration
of the deep interior of this part of Patagonia, Charles Darwin and crew
members from H. M. S. Beagle pulled three whale-boats up the
river for 18 days before returning to the Beagle in three. They
never reached Lago Argentino, the source of the river and a gateway to
the Southern Andes.
In February 2001, a group of 8 Brevard College
students and their two leaders descended the river from the Andes to the
Atlantic in sea kayaks. Click to read about the expedition of Darwin
and the Beagle crew and see how little it had changed by the
time Brevard's Voice
of the Rivers team expedition met the river.
|A distant storm across the Patagonian pampa might
occasionally mean rain. Often the precipitation does not reach the ground
due to arid conditions. Weather conditions are extremely variable due to
a nearly constant strong wind. Most of the land between the sea cliffs
and the Andes looks a lot like this.
||Most of the interior highways in Patagonia are
well- maintained gravel roads. They cross long, lonely expanses of unfenced
grassland. Guanacos (wild llamas), rheas (ostrich-like birds), foxes, and
kai-kens (geese) abound along these tracks and freely intermix with the
hundreds of thousands of sheep grazing on the pampas.
|A trip into the heart of the Southern Andes aboard
the Entre Ríos provides a magnificent opportunity to see
this pristine region of the planet preserved in the Parque Nacional
de los Glaciares.. This all-day cruise leaves Puerta Bandera
and cruises back into the Andes to the Upsala Glacier. It also stops at
an iceberg bay and at a wilderness dining room for lunch. The trip passes
numerous icebergs that calved from the various glaciers that enter the
||Had Darwin and the Beagle crew reached Lago Argentino
and the Perito Moreno glacier, he might well have postulated the occurrence
of Ice Ages, decades before Agassiz presented his evidence. On the journey
up the Río Santa Cruz, Darwin was perplexed about the presence of
large boulders that clearly must have come from the Andes lying on flat
ground at a great distance from their source. He came close to the truth,
speculating that the boulders had been rafted there by floating icebergs.
||The flanks of the peaks along Lago Argentino exhibit the structures that comprise a classic fold-thrust belt. I first visited this area in November 1989. As can be seen in the photos above, the peaks were all snow-covered. Imagine my surprise to see these amazing structures when I returned in late December 2001.
|This iceberg stands 20-30 m above the lake surface.
The alternating thin and thick bands at the base of the ice probably represent
melt-lines that took place in winter (thin) and summer (thick). These lines
suggest that this berg may have been in the lake for as long as three years.
||Large icebergs are abundant on Lago Argentino,
calving from the Perito Moreno and Upsala glaciers. This one is at least
10 m high. Remember, only 10% of an iceberg rises above the water's surface
(even less in fresh water such as this).
|The iceberg bay sits at the base of the Onelli
Glacier in the background. Small icebergs become marooned in the shallow
water of this part of the bay, on the south shore of Lago Argentino, allowing
close-up inspection of the ice.
||The first view of the Perito Moreno glacier is from the road that runs between Calafate and the glacier overlook in Glaciares National Park.
||Between 1989 and 2001, a new excursion started being offered at the glacier. For a fee, visitors can take a 1-hour boat ride out along the glacial front. Calving icebergs put out waves that rock the boat.
||The Perito Moreno valley glacier is one of the
few surging glaciers in the world. The ice descends the steep slope from
the Patagonian Ice Sheet to the narrow channel that separates the southern
arm of Lago Argentino from the main body of water to the north. The ice
wall stands about 60 m above the lake surface.
|View of the Perito Moreno glacier moments after
a large block of ice calved off into the lake. The wave in the center of
the photo is approximately 10 m high.
The ice moves about 5 m each day but most of that
is lost to the calving of icebergs. Eventually, the ice succeeds
in damming the channel causing the water level on the southern arm to gradually
rise about 40 m. When water level reaches that height, the water has sufficient
head to float the ice off of the bottom, resulting in a catastrophic draining
of the southern arm back to its original level. This jökulhlaup carves
a tunnel (seen in the photo below) upward through the ice. Instability
of the floating ice causes it to break up and retreat back across the channel.
The complete cycle takes about three years.
The front of the glacier had almost crossed and blocked the channel between the northern and southern arms of Lago Argentino by late December 2001. Not since 1988 had the lake been dammed by the ice.
See 2004 update!
||A large block of ice is shown caught in freefall
on its way to becoming an iceberg. Note the dark lines of regolith carried
up from the base of the glacier along thrust faults.
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Last updated 9/15/2004