General Category | 15-12-07 03:54 GMT | Posted by Ian Chicken

Where is it located

Ascension is a very isolated island being located in the South Atlantic Ocean.
 
It sits roughly half way between Africa (2600km) and Brazil (2232km), lying just below the Equator. The nearest land mass is Liberia some 1300km away. Although the nearest land of any sort is the Island of St Helena about 700km south east of it.


Picture courtesy of answers.com

The Islands Origin

It is like St Helena one of the peaks of the Mid-Atlantic ridge.
This ridge runs completely down the middle of the Atlantic Ocean in a North - South direction and is a weakness of the earths crust. (See Left)

The peak Iitself is some 2800 feet above sea level and is the top of a conical volcanic mountain with the base deep in the Atlantic Ocean and is roughly 10000 feet (3048m) in height.

Volcanic (extrusive) in nature and still showing this off in stark reality, though vegetation is beginning to soften this look slowly.
The island itself is roughly triangular in shape and covers approximately 34 miles² (98 km²).

Conical in its basic form and probably still in an evolutionary state, the actual mass it sits on is dated at about 5 million years old.

It is still considered geologically active and the last eruption was approximately 1000 years ago. The island has distinct features ranging from the steep sided cliffs to flat volcanic expanses to the brown conical hills which scatter the island and gives the look to the newcomer of a very barren land.

It has very distinct differences with the steep cliffs being very worn and exposed and the Lava Flows and cones still very dusty.

The cliffs where produced by massive eruptions, while the Lava flows are from massive outpourings of black lava with the cones being formed out the volcanic vents.

Its Basic Form

The islands rock formations are of volcanic (extrusive) origin, coming from lava flows or pyroclasts (fire Broken) which then fall and form deposits (tephra). with a ratio of 60:40 in favour of the pyroclasts it makes the islands form very different.
The islands exposed rock is dated at approximately 1 million years old.

There are over 50 cones on Ascension and they have a common shape more or less being steep on the South East side (due to trade winds) with a shallower slope on the other.

Examples of these are seen in the peaks that have formed, Green Mountain is formed of a Basalt base and a trachyte dome, Devils Cauldron is a caldera which was formed by explosions after the trachyte had cooled. Mountain Red Hill is Baslatic in its origin.

You then have basaltic lava flows which covers areas down to the coast.

There are also various volcanic caves on the island, they were not really known about until 1984 when Rob James (RAF) was on the island. The most common are sea caves, but the most famous are the fumaroles near Sisters Peak,  they are about 20m deep. They were formed  from Scoria, coming from the basaltic lava being blown up out of the vents


The Climate

Due to its position Ascension is in the tropical region and is very dry in nature. its temperatures varying very little over the year, 31ºC at its height to 26ºC at its lowest. with the temperature difference between sea level and the peak being about 6º. The Islands humidity sits at about 70%.

It is on the south-east trade winds and the wind constantly blows across the island. rain on the island is pretty rare on the lower levels of the island, though every now and then torrential rain will appear, these only coming after periods of years in length.

In contrast Green Mountain has frequent misty periods and can be pretty cool at times, resulting in more rainfall.