El Junco
| El Junco Laguna El Junco | |
|---|---|
|
El Junco Lagoon | |
| Location | San Cristobal, Galapagos Islands |
| Type | Crater lake |
| Primary inflows | Rainfall |
| Primary outflows | None (evaporation) |
| Max. width | 300 m (980 ft)[1] |
| Surface area | 60,000 m2 (650,000 sq ft) |
| Average depth | 4 m (13 ft) |
| Max. depth | 6 m (20 ft)[2] |
| Water volume | 360,000 m3 (13,000,000 cu ft)[2] |
| Shore length1 | 270 m (890 ft)[2] |
| Surface elevation | 700 m (2,300 ft)[3] |
| Islands | None |
| 1 Shore length is not a well-defined measure. | |
El Junco Lagoon is a lake found in the Highlands of San Cristóbal Island. Despite the name, it is a crater lake rather than a lagoon.
History
El Junco inhabits a crater formed by the collapsed caldera of an extinct volcano. Research has indicated the lake to have been extant since the end of the last ice age.[1]
Being the only source of fresh water in the Galapagos Islands, it's presence lead to the first permanent settlements on the island. The name 'El Junco" is Spanish for sedge which is endemic to the islands.
During World War II, American forces stationed at the military base on Baltra Island utilized El Junco as a primary source of water, due it being the closest available source of freshwater.[1]
The lake is currently managed by the Galapagos National Park Service.
Flooding
Due to the lake's lack of a permanent outflow, heavy rains can cause the lake to breach its banks. Several flood incidents, often corresponding to El Nino, have been recorded. Flooding in 1978 led to an outflow being recorded at 5,400 US gal (20,000 l; 4,500 imp gal) per hour. Similar events in 1978 and 1998 caused serious damage to the nearby Puerto Baquerizo Park.[2]
Ecology
Flora
The name "El Junco" is a reference to the endemic sedge (Cyperus anderssonii) which can be found growing in close proximity to the lake. Additionally, the endangered Galapagos miconia (Miconia robinsoniana) can be found in the highlands surrounding the lake. Only two populations are known to occur in the wild, the other being in the highlands of nearby Santa Cruz island.[4]
Fauna
Maybe species of birds inhabit the lake area including the endemic San Cristóbal mockingbird and White-cheeked pintail. Due to its status as an isolated source of fresh water, it is also one of the few place to witness Frigatebirds preening their feathers.[2]
Research
According a 1966 study by Dr. Paul Colinvaux, sediment at the bottom of the lagoon has a thickness of 16 m (52 ft). Using radiocarbon dating, it has been found that 3 m (9.8 ft) of the top layer were deposited during the last 10,000 years, with the remaining 13 m (43 ft) deposited during periods of drought over the course of 38,000 years, giving a total sediment age of 48,000 years.[5]
It is believed that the climate of Galapagos went through a dry period caused by glacial advances in the Northern Hemisphere, beginning 48,000 years ago and ending 10,000 years ago.