The Afar Depression, Volcanoes and Sulphuric Salt Lakes.

Geology

The Afar Depression results from the presence of a tectonic triple junction (the Afar Triple Junction) where the spreading ridges that are forming the Red Sea and the Gulf of Aden emerge on land and meet the East African Rift.

The central meeting place for these three pieces of Earth's crust is around Lake Abbe. The Afar Depression is one of two places on Earth where a mid-ocean ridge can be studied on land, the other being Iceland.

In the Depression, the earth's crust is slowly rifting apart at a rate of 1 to 2 centimeters (0.3–0.8 in) per year along each of the three rifts which form the "legs" of the triple junction. The immediate consequence of this is that there are a continuous sequence of earthquakes, fissures hundreds of meters long and deep appearing in the ground, and the valley floor sinking as much as 100 meters.

Between September and October 2005, 163 earthquakes of magnitudes greater than 3.9 and a volcanic eruption occurred within the Afar rift. 2.5 cubic kilometers of molten rock was injected into the plate along a dyke between depths of 2 and 9 km, forcing open an 8 meter wide gap on the surface.^[1]
Over millions of years, geologists expect the Red Sea to erode through the highlands surrounding the Afar Depression and flood the valley. In about 10 million years, geologists predict that the whole 6,000 km length of the East African Rift will be submerged, forming a new sea as large as the Red Sea is now. At that point, Africa will have lost its horn.^[2]


The floor of the Afar Depression is composed of lava, mostly basalt. One of Earth's great active volcanoes, Erta Ale, is found here. The Afar Depression is, in the views of some geologists, underlain by a mantle plume, a great upwelling of mantle that melts to yield basalt as it approaches the surface.

Location of the depression and local fault lines.

Perspective view of the Afar depression and environs, generated by draping a Landsat image over a Digital elevation model. Image generated by Allison Thurmond.

Simplified geologic map of the Afar Depression, after A.Beyene and M.G.Abdelsalam (2005).

 

Environment

Erta Ale shield volcano in the Danakil Desert.

Lake Assal, with the salt pan on the left.

Lake Assal.

The lowlands of the Afar Depression are dominated by heat and drought. There is no rain for most of the year, and yearly rainfall averages range from 100 to 200 millimeters (4 to 7 in), with less rain falling closer to the coast. The settlement of Dallol in northern Ethiopia holds the record high average temperature for an inhabited location on Earth, where an average annual temperature of 34°C (94°F) was recorded between the years 1960 and 1966. Dallol is also one of the most remote places on Earth. There are no roads; the only regular transport service is provided by camel caravans which travel to the area to collect salt. Nearby is the Dallol volcano, which last exploded in 1926.
The Awash River, flowing northeastward through southern Afar, provides a narrow green belt and enables life for the flora and fauna in the area and for the Afars, the nomadic people living in the Danakil desert. The Awash River, contained completely within the boundaries of Ethiopia, is the only river that flows into the Depression. It is the principal stream of an endorheic drainage basin covering parts of the Amhara, Oromia and Somali Regions, as well as the southern half of the Afar Region.


About 128 kilometers (79 miles) from the Red Sea, the Awash ends in a chain of salt lakes, where its water evaporates as quickly as it is supplied. About 1200 km² (463 sq mi) of the Afar Depression is covered by salt, and salt mining is still a major source of income for many Afar tribes.


The Middle Awash is an archaeological site along the Awash River. A number of Pleistocene and late Miocene hominid remains have been found at the site, along with some of the oldest known Olduwan stone artifacts and patches of fire-baked clay. The Middle Awash contains the site of Hadar, where Australopithecus afarensis, including the famous "Lucy" partial skeleton and the "First Family" were discovered. Not only hominids, but also elephantoids, crocodiles and hippopotamus remains have been found in this region.
Also within the Afar Depression is the Danakil Desert, which lies in northeastern Ethiopia and in southern Eritrea and much of Djibouti. The Danakil's main industry is salt mining, while it is also home to wildlife, including African wild asses.
The desert is the homeland of the Afar people, the majority of whom have remained nomadic pastoralists, raising goats, sheep, and cattle in the desert. During the dry season, most move to and camp on the banks of the Awash River. Camels comprise the most common means of transportation as the Afar nomads move from watering hole to watering hole. With the arrival of the rainy season in November, most relocate to higher ground in order to avoid both flooding and mosquitos.


Lake Assal is a crater lake in central Djibouti, located at the southern border of Tadjoura Region, touching Dikhil Region, some 120 km (75 mi) west of Djibouti city. It lies 155 m (515 ft) below sea level; its shores comprise the lowest point on land in Africa.

Lake Assal is one of the most saline bodies of water on the earth, with a 34.8 percent salt concentration (up to 40 percent at 20 m (66 ft) depth). The sources of the lake are hot springs whose salinity is close to sea water, which are fed by the Gulf of Tadjoura, the eastern extension of the Gulf of Aden, specifically the nearly closed-off bay Ghoubet Kharab, about 10 km southeast of the lake.

The lake area is wild and desert-like, and no fauna or flora can be seen in the syrupy waters of the lake. The high temperature of the water (33-34 °C) favors evaporation, and it is surrounded by a salt pan which extends west and mainly northwest. The salt is mined and transported by caravan to Ethiopia.

Plant and animal life

Camel caravan on the shores of Lake Assal.

The Afar Depression biome is characterized as desert scrubland. Vegetation is mostly confined to drought-resistant plants such as small trees like species of the dragon tree, shrubs, and grasses.

Wildlife includes many herbivores such as Grevy's Zebra, Soemmering’s Gazelle, Oryx Beisa and, notably, the last viable population of African wild ass (Equus africanus somalicus). Birds include the ostrich, the endemic Archer's lark (Heteromirafra archeri), the Secretary Bird, Arabian and Kori bustards, Abyssinian Roller, and Crested Francolin.

In the southern part of the plain, in Ethiopia, lies the Mille-Sardo Wildlife Reserve, which was established 1973. The reserve covers 3,385 square miles (8,766 square km).

http://www.newworldencyclopedia.org/entry/Afar_Depression

Agia Varvara Shipwreck Red Sea

AGIA VARVARA Shipwreck  Location:	28° 03' 42" N, 34° 26' 40"E. Southern Gulf of Aqaba on east coast of Sinai Peninsular
Access:	Day boat from Sharm El Sheikh
Minimum Depth to Wreck	6m (at Bows)
Maximum Depth to Seabed:	22m (at stern)
Average Visibility:	20-25m

The Ship

Built by Ch & At, Aug-Normand of France, the Agia Varvara was launched as the "Nina" in 1950. 

Officially described as a General Cargo Vessel, she was later called Athenia and then Petros before being finally re-named Agia Varvara in 1974. 

A relatively small ship for one with 3 cargo holds, she displaced 985 grt and had a 5 Cylinder Oil-fired engine capable of producing 750 bhp and a top speed of 10 Knots. She was 73.2m x 9.33m - with a draught of 4m.

The Agia Varvara was owned and operated by the Gestar Shipping Company of Famagusta, Cyprus at the time of her loss.

The Loss of the Agia Varvara

On 27 June 1976, the Agia Varvara sailed in ballast from the Jordanian port of Aqaba destined for Port Said. The ship was only 90 miles further south when, in the early hours of the following morning, she drove hard onto the inshore Reef near Nabq - a few miles north of Sharm El Sheikh. The crew were subsequently rescued by the Israeli Navy.

Getting the right Name!

The word "Agia" is pronounced with a silent "g" and this has led to several wrongly spelled versions of the name. One of the leading authorities on shipwrecks includes details of this vessel’s loss under the misnomer "Ayia Varvara." Even Lloyd’s List of 29 June 1976, describes the vessel as the "Aghia Barbara!"

Diving the Agia Varvara

We departed from Na’ama Bay heading in a northerly direction and it was not long before we were passing close to the four Reefs which mark the centre of the narrow interface between the Red Sea and the Gulf of Aqaba. Here the rule of the road is keep right with "up" traffic taking the eastern route between the reefs and Tiran Island and "down" traffic keeping to the west. Jackson Reef is the most northerly of the four reefs and Gordon Reef the most southerly. Ominously, they are both marked by the prominent shipwrecks "Lara" and "Loullia" respectively - a clear warning for all vessels entering and leaving the Gulf of Aqaba to exercise extreme care.

From some distance away we could see the superstructure of the Million Hope - one of the largest ships ever to have been lost in the Red Sea and one which acts as a marker for the Agia Varvara. In no time at all we were passing alongside this massive ship - the keel of which rests on the seabed 20m below. Two hundred metres further on we saw some remnants of wreckage on the reef top. These were once the Bows of the Agia Varvara and almost immediately we could see the rest of this vessel underwater. It was time to get wet.

A combination of a relatively shallow attitude and an exposed position mean that after 25 years the vessel is now rather broken up - although there are some very large sections for those who enjoy exploring the "big" bits. The stern is found resting on the seabed at 20m and pointing up the reef. All the portholes are still in place and the very bent propeller is still attached. The rudder, however, is not and is found a short distance away. Above the stern, the diver is able to investigate inside the lower part of the bridge castle which allows access down to the engine room. Curiously, a large portion of the engines lie exposed on the reef at 6-8m.

A few metres to the north is another large section of superstructure. This is  the upper part of the bridge castle which has become entirely separated and now rests on the seabed at 20m. Trapped underneath is the ship’s funnel - on its side of which is an open access door.  The Coral

Reef towers over the wreckage here large pieces of steel plating and iron cross-members are also found - and yet more a short distance even further to the  north.

The foc’sle and bows appear to have remained on the surface of the reef and, over a period of 25 years, have been reduced to a few remnants of scrap metal and the occasional bollard.

Postscript

It must be said that the Agia Varvara is not one of Egypt’s greatest shipwrecks. Had she been wrecked elsewhere, I am sure that would have been very different. Of course, she is where she is, and being largely overlooked she provides a refreshing alternative to those shipwrecks which have been systematically looted by those who think only of themselves.  It was interesting to discover that Paolo Guiotto (an excellent Dive Guide by any standards) was not the only local Dive Guide who had never dived this wreck before. The Agia Varvara is, nevertheless, a very interesting dive.  When viewed alongside the Dunraven, Million Hope and Zingara, she is one of only four diveable wrecks within easy reach of Sharm El Sheikh and could, therefore, play a more important role for those divers wishing to

experience something new in this corner of the Egyptian Red Sea.
http://www.touregypt.net/VDC/agiavarvara.htm