Friday, July 30, 2010

[Geology2] The Chocolate Hills of Bohol



  
 
 

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via Kuriositas by noreply@blogger.com (RJ EVans) on 7/30/10

Bohol in the Philippines is home to a dramatically unusual geographic feature – the Chocolate Hills. A shame, but a certain Mr Wonka has not been visiting (and neither is this the entrance to the fabled land of the Oompa Loompas). In the summer the lush green grass that covers the hills turns brown and it is this, rather than any fictional intercession which gives the place its name.

No one has (strangely) ever counted the exact amount of these haycock hills. However, it is thought that there are up to 1800 of them dotted around the central area of the island of Bohol. Yet, what gives the hills their conical (or at least dome like) shape? Could they perhaps be man-made ancient burial chambers?

Although there are, unsurprisingly, many myths which surround these almost symmetrical hills, they are the product of natural processes rather than anything mankind has produced. The hills are made of limestone which has then been covered with topsoil on which grass then has grown.

They are not simply bumps in the ground either. The largest one rises almost 400 feet in height above the plane of Bohol although generally they tend to be between 100 and 160 feet in height. Their height and their sheer number has meant that they have been the primary source of income through tourism for the nearby town of Carmen.

In the dry season where there is virtually no rain the hardy grass on the hills dries up (but does not die) and the hills get their chocolate color. It is said that the hills get their name from the Hershey confection known as Chocolate Kisses (above) but this sounds something of a chicken and egg situation, in truth. Although the Hershey treat has been around since 1907 the hills have been here a lot longer.

The limestone of the hills is actually called karst. This topography is caused when layers of bedrock made up of a soluble substance such as dolomite or in this case limestone.  The landscape has been slowly eroded through a process called solvation. The hills are that which is left behind. You can visit some other pages which feature karst formations at the bottom of this article.

The shape of the hills, known as a geomorphologic structure, is known as a mogote. Although they have been formed through the solvation of their limestone by thousands of years of rain there is another factor in Bohol.
There is a great deal of erosion by rivers after they had been uplifted above sea level. The farmland that separates the hills is full of rivers and caves with underground springs and these have contributed to the unique shape of the Chocolate Hills.

As with any unusual geographical feature, local legends abound as to how they got there in the first place. One story involves a pair of giants who fell out with each other. They fought by hurling huge rocks at each other until they were exhausted. Once they awoke they forgot their differences and departed but didn't bother to do any cleaning up.

If you are more of a romantic you may prefer the legend of Arogo and Aloya. Like our friends above, Arogo was a giant but Aloya was mortal and she had a much shorter lifespan. When Aloya threw off her mortal coil, Arogo was so bereft that he shed giant tears which formed the Chocolate Hills where they landed.

Several other legends are also notable for their insistence that the hills were formed by the bodily functions of either a giant who was desperate to slim down or a giant moose with a stomach upset. Both of these stories, had they gained preference, would have meant the Chocolate Hills could have ended up with an entirely different name – and not one entirely suited to family vacations.

The hills were declared a national geographical monument in 1988 but mining was still levelling a number of the hills as recently as 2006. Even though UNESCO World Heritage status has been applied for the Chocolate Hills are still perceived as viable sites for small scale quarries by many locals. The greatest challenge for the future will be to balance the needs of local people with the obvious requirement that the hills are preserved for future generations to enjoy.

You may also like:

The Giant Mushrooms of Beli Plast

Local legend has it that the giant stone mushrooms of Beli Plast are in fact the severed heads of four sisters, who after fleeing an oppressor were pursued.  He beheaded them as punishment for daring to run and here they remain to this day.
 
Image Credit Flickr User Clearchos



The Tufa Towers of Mono Lake
In the early nineteen forties the city of Los Angeles was growing quickly. The Second World War was in full flow and when it came to the environment it was felt that some things could be neglected. The LA Department of Water and Power began diverting the lakes streams three hundred and fifty miles to the south. The damage to the environment would be untold. Paradoxically it would leave the area eerily beautiful – like some alien backdrop from an episode of Star Trek.

Image Credit Flickr User Alaskan Guy

 
 

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