The Cave Of Crystals

The Cave of Crystals

The cave of crystals or Cueva de los Cristales- is an amazing geological formation in Mexico.

This is a cave connected to the Naica mine that sits 300m below the surface.

The main chamber contains giant gypsum crystals.


The largest crystal that has been found to date is 11 m in length and weighs 55 tonnes.


The cave is really hot with 90-99% humidity and it is due to these factors that the cave is as of yet realtivly unexplored as without the proper protection people can only have 10 minutes exposure at any one time.


Formation of the crystals


Naica lies on an ancient fault and there is an underground magma chamber below the cave. The magma heated the ground water and it became saturated with minerals, including large quantities of gypsum. The hollow space of the cave was filled with this mineral-rich hot water and remained filled for about 500,000 years. During this time, the temperature of the water remained very stable at over 50 °C. This allowed crystals to form and grow to immense sizes

 Discovery

In 1910 miners discovered a cavern beneath the Naica mine workings, the Cave of Swords (Spanish: Cueva de las Espadas). It is located at a depth of 120 m, above the Cave of Crystals, and contains spectacular, smaller (1 m long) crystals. It is speculated that at this level, transition temperatures may have fallen much more rapidly, leading to an end in the growth of the crystals.

The Giant Crystal cave was discovered in 2000 by miners excavating a new tunnel for the Industrias Peñoles mining company located in Naica, Mexico, while drilling through the Naica fault, which they were concerned would flood the mine. The mining complex in Naica contains substantial deposits of silver, zinc and lead.

The Cave of Crystals is a horseshoe-shaped cavity in limestone rock. Its floor is covered with perfectly-faceted crystalline blocks. Huge crystal beams jut out from both the blocks and the floor. The caves are accessible today because the mining company's pumping operations keep them clear of water. If the pumping were stopped, the caves would again be submerged. The crystals deteriorate in air, so the Naica Project is attempting to visually document the crystals before they deteriorate further.

A further chamber was found in a drilling project in 2009. The new cave, named the Ice Palace, is 150 m deep and is not flooded, but its crystal formations are much smaller, with small 'cauliflower' formations and fine, threadlike crystals

Exploration hinted at the existence of further chambers, but further exploration would have required demolition of the crystals. It was stated that the cave would eventually be resealed and the water level allowed to rise again.

Ol Doinyo Lengai

Ol Doinyo Lengai is an active volcano located in the north of Tanzania and is part of the volcanic system of the East African Rift. It is located in the eastern Rift Valley, or Gregory Rift, south of both Lake Natron and Kenya. It is unique among active volcanoes in that it produces natrocarbonatite lava, a unique occurrence of volcanic carbonatite. Further, the temperature of its lava as it emerges is only around 510 °C (950 °F). A few older extinct carbonatite volcanoes are located nearby, including Homa Mountain.

Ol Doinyo Lengai" means "The Mountain of God" in the Maasai language of the native people. The record of eruptions on the mountain dates to 1883, and flows were also recorded between 1904 and 1910 and again between 1913 and 1915. A major eruption took place in June 1917, which resulted in volcanic ash being deposited about 48 kilometers away.

A similar eruption took place for several months in 1926 and between July and December 1940, resulting in the ash being deposited as far as Loliondo, which is 100 kilometres away. Several minor eruptions of lava were observed in 1954, 1955, 1958 the early 1960s.

When Ol Doinyo Lengai erupted on August 14, 1966, two geologists — J. B. Dawson and G. C. Clark — who visited the crater a week later, reported seeing “a thick column of black ash” that rose for approximately three thousand feet above the volcano and drifted away northwards towards Lake Natron. When the two climbed the cone-shaped vent, they reported seeing a continuous discharge of gas and whitish-grey ash and dust from the centre of the pit.

Volcanic activity in the mountain caused daily earth tremors in Kenya and Tanzania beginning on July 12, 2007. The latest to hit parts of Nairobi city was recorded on July 18, 2007 at 8.30pm (Kenyan Time). The strongest tremor measured 6.0 on the Richter scale. Geologists suspected that the sudden increase of tremors was indicative of the movement of magma through the Ol Doinyo Lengai. The volcano finally erupted on September 4, 2007, sending a plume of ash and steam at least 18 kilometers downwind and covering the north and west flanks in fresh lava flows. The eruption has continued intermittently into 2008, as of the end of February it was reported that the eruption appeared to be gathering strength, with a major outburst taking place on March 5. During April periods of inactivity have been followed by eruptions on April 8 and 17. Eruptive activity continued until late August 2008. A visit to the summit in September 2008 discovered that lava emission had resumed from two vents in the floor of the new crater. Visits to the crater in March/April 2009 showed that even this activity appears to have ceased

Whereas most lavas are rich in silicate minerals, the lava of Ol Doinyo Lengai is a carbonatite. It is rich in the rare sodium and potassium carbonates, nyerereite and gregoryite. Due to this unusual composition, the lava erupts at relatively low temperatures of approximately 500-600 degrees Celsius. This temperature is so low that the molten lava appears black in sunlight, rather than having the red glow common to most lavas. It is also much more fluid than silicate lavas, often less viscous than water. The sodium and potassium carbonate minerals of the lavas formed by Ol Doinyo Lengai are unstable at the Earth's surface and susceptible to rapid weathering, quickly turning from black to grey in color. The resulting volcanic landscape is different from any other in the world.

The rift Valley

The rift valley – also known as the Great Rift Valley or the East African rift.

Basic Information.

The East African Rift is an active continental rift zone in eastern Africa that appears to be a developing divergent tectonic plate boundary. In the past it was considered to be part of a larger Great Rift Valley that extended north to Turkey. The rift is a narrow zone in which the African Plate is in the process of splitting into two new tectonic plates called the Somali Plate and the Nubian Plate, which are sub plates or protoplates.

The East African Rift runs from the Afar Triple Junction in the Afar Depression southward through eastern Africa. It is believed to run offshore of the coast of Mozambique along the Karimba and Lacerda rifts or grabens, terminating in the Andrew Bain Fracture Zone complex, where it is believed to have its junction with the Southwest Indian Ridge.

In simple terms, a rift can be thought of as a fracture in the earth's surface that widens over time, or more technically, as an elongate basin bounded by opposed steeply dipping normal faults. Geologists are still debating exactly how rifting comes about, but the process is so well displayed in East Africa (Ethiopia-Kenya-Uganda-Tanzania) that geologists have attached a name to the new plate-to-be; the Nubian Plate makes up most of Africa, while the smaller plate that is pulling away has been named the Somalian Plate. These two plates are moving away from each other and also away from the Arabian plate to the north. The point where these three plates meet in the Afar region of Ethiopia forms what is called a triple-junction. However, all the rifting in East Africa is not confined to the Horn of Africa; there is a lot of rifting activity further south as well, extending into Kenya and Tanzania and Great Lakes region of Africa. The purpose of this paper is to discuss the general geology of these rifts are and highlight the geologic processes involved in their formation.

The East African Rift consists of two main branches called the Gregory Rift and the Western Rift Valley. These result from the actions of numerous normal (dip-slip) faults which are typical of all tectonic rift zones. The Eastern Rift Valley includes the Main Ethiopian Rift, running eastward from the Afar Triple Junction, which continues south as the Kenyan Rift Valley. The Western Rift Valley includes the Albertine Rift, and further south the valley of Lake Malawi.

The East African Rift Zone includes a number of active as well as dormant volcanoes. These include Mount Kilimanjaro, Mount Kenya, Mount Longonot, Menengai Crater, Mount Karisimbi, Mount Nyiragongo, Mount Meru and Mount Elgon as well as the Crater Highlands in Tanzania. The Ol Doinyo Lengai volcano remains active, and is currently the only natro-carbonatite volcano in the world. Erta Ale is a continuously active basaltic shield volcano in the Afar Region of northeastern Ethiopia.

Formation.

The exact mechanism of rift formation is an on-going debate among geologists and geophysicists. One popular model for the EARS assumes that elevated heat flow from the mantle (strictly the asthenosphere) is causing a pair of thermal "bulges" in central Kenya and the Afar region of north-central Ethiopia. These bulges can be easily seen as elevated highlands on any topographic map of the area (Figure 1). As these bulges form, they stretch and fracture the outer brittle crust into a series of normal faults forming the classic horst and graben structure of rift valleys. Most current geological thinking holds that bulges are initiated by mantle plumes under the continent heating the overlying crust and causing it to expand and fracture. Ideally the dominant fractures created occur in a pattern consisting of three fractures or fracture zones radiating from a point with an angular separation of 120 degrees. The point from which the three branches radiate is called a "triple junction" and is well illustrated in the Afar region of Ethiopia where two branches are occupied by the Red Sea and Gulf of Aden, and the third rift branch runs to the south through Ethiopia.

The stretching process associated with rift formation is often preceded by huge volcanic eruptions which flow over large areas and are usually preserved/exposed on the flanks of the rift. These eruptions are considered by some geologists to be "flood basalts" - the lava is erupted along fractures (rather than at individual volcanoes) and runs over the land in sheets like water during a flood. Such eruptions can cover massive areas of land and develop enormous thicknesses (the Deccan Traps of India and the Siberian Traps are examples). If the stretching of the crust continues, it forms a "stretched zone" of thinned crust consisting of a mix of basaltic and continental rocks which eventually drops below sea level, as has happened in the Red Sea and Gulf of Aden. Further stretching leads to the formation of oceanic crust and the birth of a new ocean basin.

If the rifting process described occurs in a continental setting, then we have a situation similar to what is now occurring in Kenya where the East African/Gregory Rift is forming. In this case it is referred to as "continental rifting" (for obvious reasons) and provides a glimpse into what may have been the early development of the Ethiopian Rift.

the rifting of East Africa is complicated by the fact that two branches have developed, one to the west which hosts the African Great Lakes (where the rift filled with water) and another nearly parallel rift about 600 kilometres to the east which nearly bisects Kenya north-to-south before entering Tanzania where it seems to die out . Lake Victoria sits between these two branches. It is thought that these rifts are generally following old sutures between ancient continental masses that collided billions of years ago to form the African craton and that the split around the Lake Victoria region occurred due to the presence of a small core of ancient metamorphic rock, the Tanzania craton, that was too hard for the rift to tear through. Because the rift could not go straight through this area, it instead diverged around it leading to the two branches that can be seen today.

As is the case in Ethiopia, a hot spot seems to be situated under central Kenya, as evidenced by the elevated topographic dome there. This is almost exactly analogous to the rift Ethiopia, and in fact, some geologists have suggested that the Kenya dome is the same hotspot or plume that gave rise to the initial Ethiopian rifting. Whatever the cause, it is clear that we have two rifts that are separated enough to justify giving them different names, but near enough to suggest that they are genetically related.

In conclusion the rift valley is spreading and will eventually split apart completely forming the Nubian and Somalian plate.

Update!!!!- 18/02/2016
so- as the rift valley is one of my favorite things!!!

I have recently become involved with a project- GeomissionUganda that seeks to help establish sustainable geological tourism on the east Albertine rift- part of the Rift valley! we aim to set up a route that encorperates much of the amazing geology that Ugnada's Albertine rift offers as well as teaching about it and trainging rangers in both the uk and Ugnada, how to make the most of what this beautiful country has to offer!  We will be traveling there in September to start getting things done in order for the main trip in 2017! However to do this we need to raise funding which is where our crowdfunding campaign comes in!So please take a look and hopefully fund us! For more information see the blog post I put up yesterday!!! 

Cheers

AJ 

Erta Ale

 

 I have to admit... to me the most fascinating part of either Geology or Geography has to be volcanoes.

I  think that one of the volcanoes and its surrounding areas that has most caught my eye and kept my interest for the longest is Erta Ale at the Danakil depression in Ethiopia.  

Erta Ale is a continuously active shield volcano in the Afar region.

It is 613 metres high with a base with a diameter of nearly 30km. The summit caldera contains two large steep-sided pit craters, the N and S (or "central") pit craters, and one smaller pit at the south-east side of the N pit. The caldera appears to have been formed by 3 overlapping circular collapse structures and has approximate dimensions of 1600 x 700m.  It always has one-sometimes 2 active lava lakes at the summit that occasionally over flow on the south side of the volcano.

It is the longest existing lava lake- it has been there since the early years of the 20^th century and is one of only 4 in the world- one other is Niriagongo- in the Congo.

It is known as the smoking mountain in local language and the southern lake is known as the gateway to hell.

Its last major eruption was on September 25^th 2005 that killed 250 livestock and forced thousands of people to have to flee- there was yet another lava flow in august 2007 that forced the evacuation of hundreds and leaving 2 people missing. A further eruption was reported on November 4^th 2008 by the scientists at Addis Ababa University.

In November 2010 following a period in which the lava lakes had been rising there were several short lava flows that emitted from the north lake, and a cone was built up around the lake due to the constant overflows.

By the end of January 2011 another small lake was observed around 10m below the crater floor.

This volcanic formation is the result of the splitting of the African rift valley that will eventually form two new plates- the Somalian and the Nubian plates.

As can be seen on this map- the two plates are spreading apart gradually giving us what is the red sea fault as well as the fault that runs down the east of Africa- now eventually probably in around a million years these two plates will finish splitting apart and form two new plates.