Réunion Island

Merry Christmas, Happy New Years, etc., etc., to everyone out there. Since it is cold, wet, and nasty outside my home today in North Carolina, I decided to head to warmer climes for this little essay – specifically, Réunion Island.

Réunion Islands (Wikimedia Commons)

Satellite view of Réunion. Map and Photo source – Wikipedia

Réunion Island is a small island in the Indian Ocean that has been under the rule of various countries since its first discovery by Arab sailors in the 1100’s. It was first lightly inhabited in the 1500’s by the Portuguese, then truly colonized in the1600’s by the French. Like many other such islands, it was first used as a penal colony (due to its remoteness, I suspect), then further settled by a variety of peoples (Chinese, Muslim, Indian, etc.), creating a vibrant Creole community. It has a small population of about 840,000 that is concentrated mainly along the coastline. It is located in the Indian Ocean, east of Madagascar, about 200 kilometers (120 mi) southwest of Mauritius, the nearest island.

The island is a hot-spot island whose above sea level size is all of 63 kilometers by 45 kilometers (39 x 28 miles). As usual with these types of islands, it total size is much more substantial – it is a shield volcano that is 7 km high, and has a diameter of 220-240km, so that < 5% of its mass is above the water. It is heavily forested and has the standard tropical coral reef system surrounding it.
Réunion is home to one of the world’s most active volcanos, the Piton de la Fournaise (appropriately, Furnace Peak), which has erupted more than 170 times since the mid-17th century. Various lava flows have closed roads and damaged buildings.

Lava Flow from Piton de la Fournaise. Source Wikipedia.

The volcano rises more than 2,631 metres (8,632 ft) above sea level and is sometimes called a sister to Hawaiian volcanoes because of the similarity of climate and volcanic nature. It has erupted more than 100 times since 1640 and is under constant monitoring. It most recently erupted in January of 2010. Before that, the most noticeable was during April 2007, when the lava flow was estimated at 3,000,000 cubic metres (3,900,000 cu yd.) per day. The Piton de la Fournaise is created by a hotspot volcano, which also created the Piton des Neiges and the islands of Mauritius and Rodrigues.
It has two other volcanos – Alizes and the Piton des Neiges (the name means Snow Peak, which is a bit of a misnomer as snow is an extremely rare occurrence on the island). The Alizes volcano ceased erupting about 530,000 years ago, and has been overtaken by the Piton des Neiges, which has been dormant for about 12,000 years and is now marked by a trio of heavily eroded calderas in the summit area. The Piton des Neiges volcano, at 3070 meters (10,070 ft.), is the highest point on the island. The calderas – the Cirque de Salazie, the Cirque de Cilaos and the Cirque de Mafate, are open to the east, with the last being accessible only on foot or by helicopter.

The volcanic history actually starts with the hotspot that created the Deccan Traps – Réunion Island is the just the latest manifestation of that hotspot. This has been determined by the chemical signature of the basalt, tracing back through Mauritius Island to the Deccan Traps themselves.

One of the latest findings about the ocean floor here is that it appears that a micro-continent, Mauritia, is buried beneath the lavas extruded by the hot spot. This continent fragment broke off as the ocean opened between Madagascar and India, and then got buried under lava as time went by.

Now back to the island itself – the initial volcanos on the island were Alizes and Piton des Neiges. Alizes stopped erupting about 530,000 ya, and was overtaken by Piton des Neiges. Piton des Neiges’ last eruption was about 12,000 ya. At about the time that Alizes stopped, Piton de la Fournaise appeared as the hot spot moved west. Piton des Neiges stopped erupting about 12,000 ya, and all activity now occurs at Piton de la Fournaise.
The Piton des Neiges edifice shows multiple construction/dismantling phases, with the outcrop formations showing intensively weathered rocks and debris avalanche deposits, intruded by dikes. Piton de la Fournaise shows two main phases – 530,000 – 150,000 ya and 150,000 – 0 ya, with a large landslide separating the two. As a result of the slide, the center of the volcano has shifted eastward to its present location. There appears to have been at least two caldera collapses in this latest phase, which are still being debated. The resulting structures are the Plaine des Sables, the Enclos depression, and the Grand Brûlé. Since the formation of the Enclos depression 4500 ya, the volcanic activity is mainly restricted to the caldera. Only few eruptions occurred along the NE and SE rift zones, in the Plaine des Sables and in the Rivière des Remparts.

If you have the chance to travel to Reunion (as I sign wistfully – someday, someday….) , one of the more notable features to visit is where some basaltic columns are showing along the Bras de la Plaine River, which runs through the basalt plateau between the two volcanoes.

Réunion Island basalt. Photo from: http://epod.usra.edu/blog/2011/08/reunion-island-basalt.html. Photo taken July 14, 2011.

And now for a bit of temptation – one of my favorite holiday treats:
Fire and Ice Candy (a version of Peppermint Bark)
A tasty treat that has the bite of spicy Cinnamon candy blended with the smooth creaminess of white chocolate.

1 pound white chocolate, broken up
4 ounces any hard strong spicy cinnamon candy, broken (smashed) into pieces (in the US, think Red Hots).

Requires a double boiler, parchment paper, and a cookie sheet.
Cover cookie sheet with parchment paper. If you cannot get the paper, lightly grease the cookie sheet.
Get the water boiling in the bottom ½ of the boiler, then remove from the heat.
Melt the chocolate in the top half of the boiler, stir in candy.
Pour the mix onto the cookie sheet and spread very thin.
Cool until it hardens, then break up into bite-sized pieces and enjoy.

Note – Finding the cinnamon candy can be difficult, I get mine at a store that specializes in candy and cake fixings and utensils.

This can actually be made with any type of strongly flavored hard candy – peppermint, lemon, butterscotch…..

Fran

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