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Chocolate Hills

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The Chocolate Hills are a unique geological formation located in the Philippine province of Bohol. These hills consist of a massive collection of mounds that create a rolling, uneven landscape. Scientists estimate there are at least 1,260 individual hills, though some counts suggest there may be as many as 1,776. They spread across an area of more than 50 square kilometers. Because of their striking appearance, they are featured on the provincial flag and seal of Bohol.

Philippine Island - Bohol - NARA - 68156390
Philippine Island - Bohol - NARA - 68156390

These hills are famous for a dramatic change in color that happens every year. Most of the time, the mounds are covered in lush green vegetation. The plant life is dominated by grass species like *Imperata cylindrica* and *Saccharum spontaneum*. However, during the dry season, this grass dries up. The vegetation turns a deep chocolate-brown color, which gives the hills their name. In the flatlands located between the hills, farmers cultivate rice and other cash crops.

Bohol Hills 3, Carmen, Philippines
Bohol Hills 3, Carmen, Philippines

The hills are actually made of limestone, a type of rock formed from ancient sea life. Specifically, they are composed of Late Pliocene to Early Pleistocene marine limestone. This rock is thin to medium-bedded and can be sandy or rubbly. Because it formed in the ocean, the limestone contains many fossils. You can find remains of coral, mollusks, algae, and shallow marine foraminifera within the stone.

Chocolate Hills historical marker
Chocolate Hills historical marker

Geologists call these formations conical karst. This term describes a landscape shaped by the way water interacts with certain rocks. The process began when these limestone layers were uplifted above sea level. This movement was caused by tectonic processes, which are shifts in the Earth's crust. Once the rock was above the water, it was fractured. Then, a combination of rainfall, surface water, and groundwater began to dissolve the limestone. This chemical dissolution, along with erosion from streams, carved the rock into the symmetrical, dome-shaped mounds we see today.

Chocolate Hills historical marker
Chocolate Hills historical marker

While many people have suggested different origins, science has ruled out several popular theories. Some people once believed the hills were created by sub-oceanic volcanism or volcanic eruptions. However, geologists have found no exposed or associated volcanic rocks in the area. Other theories suggested that tidal movements or massive geological shifts created the mounds. Scientists note that these ideas lack the corroborating evidence needed to prove they are true. The karst dissolution process remains the most accurate scientific explanation.

The Chocolate Hills are highly significant to the Philippines and are protected by law. The National Committee on Geological Sciences declared them a National Geological Monument on June 18, 1988. In 1997, President Fidel V. Ramos signed Proclamation No. 1037 to further protect the area. In July 2018, the hills were officially declared a national park under the Expanded National Integrated Protected Areas System Act. The government also submitted the site to UNESCO to be considered for the World Heritage List.

Bohol chocolate hills
Bohol chocolate hills

Despite these protections, the hills face several modern challenges. One major concern is the conflict between tourism, mining, and land use. Some hills were originally classified as private land, which led to social unrest and conflicts with groups like the New People's Army. Additionally, quarrying activities for construction materials can threaten the natural vegetation. The hills have also faced natural disasters. In 2013, a magnitude 7.2 earthquake struck near Sagbayan, causing one hill to give way and destroying a viewing deck. More recently, in April 2024, a grass fire burned two hills in Carmen.

Bohol chocolate hills
Bohol chocolate hills
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🖼️ Images & Media (4)
File:Bohol chocolate hills.png
Bohol chocolate hills.png
File:Bohol Hills 3, Carmen, Philippines.jpg
Bohol Hills 3, Carmen, Philippines.jpg
File:Chocolate Hills historical marker.jpg
Chocolate Hills historical marker.jpg
File:Philippine Island - Bohol - NARA - 68156390.jpg
Philippine Island - Bohol - NARA - 68156390.jpg
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