Guilin geology Archives - Tour GuizhouTour Guizhou

written about Guilin, but applies to Guizhou’s karst as well: “Guilin’s most renowned feature is its dramatic karst terrain. Rising sharply at odd angles, limestone peaks look like giant teeth growing out of the green plain. Karst topography is characterized by many caverns and sinkholes that form by the dissolution of limestone or other carbonate rocks. Florida and Virginia’s Shenandoah Valley are good examples of where karst can be found in the United States. However, the topography looks completely different from that in China, thanks to conditions that exposed China’s karst and eroded its softer limestone faster. The specific conditions for forming the magnificent topography of Guilin “are fourfold,” according to Ray Beiersdorfer, a geologist at Youngstown State University in Ohio. “First, you need hard, compact carbonate rock. In Guilin, it’s Devonian limestone. Secondly, you need strong uplift, in this case provided by the collision of India with Asia to form the Himalaya. Third, you need a Monsoon climate of high moisture during the warmest season. Finally, the area must not have been scoured by glaciers, which this region wasn’t.”

Two types of karst landscapes predominate in Guilin: fenglin or peak forest (isolated towers) and fengcong or peak cluster (linked-base towers). The two types may have evolved sequentially from peak forest to peak cluster, or they may have evolved simultaneously. Beiersdorfer described this landscape, which he saw during a recent visit to China: “China in general and the Guilin area specifically boasts some of the most spectacular karst topography in the world.” ” (from www.geotimes.org/apr07/article.html?id=Travels0407.html )

Karst
Huge areas of China’s Southwest comprise visually spectacular landscapes featuring karst – weathered limestone formations. In China, limestone has been created from fossilized prehistoric sea floor sediments, brought to the surface by geological upheavals. The exposed alkaline limestone is then eroded by naturally-occurring acidic rain. Above ground, this results in anything from closely packed “stone forests,” poking a few meters skywards, to the huge conical hills covering half of Guizhou, and the tall, elegant pinnacles around Guilin. Underground, percolating water and subterranean rivers carve out long, interlinked caverns, hung with oddly shaped rock formations.
Karst formation
Southwest China’s thick and fractured pure limestone has led to a dramatically eroded landscape. The warm wet climate speeds up the weathering of limestone by acid rainwater and chemicals in rotting plants.
1. Surface streams lose water to cave systems developing in the limestone. Surface drainage is diverted down sink holes to below the water table.
Karst landscape
This cut-away artwork shows an idealized karst landscape, with all the features shown together. Karst topographies usually have a thick layer of cave-ridden limestone, and then, depending on the area’s geology and the age of the formation, a few of the features shown here.
Fenglin karst, which translates as peak-forest karst, is characterized by peaks that rise near vertically, like trees, 100 to 250 feet (30 to 80 m) above the surrounding flat floodplains. These dramatic tower-like karsts are found in and around the city of Guilin.
1. Surface streams lose water to cave systems developing in the limestone. Surface drainage is diverted down sink holes to below the water table.2. Peaks develop from the land left after erosion by the streams. The cave system gets larger as fast-moving subsurface streams bore through the limestone, and the water table drops.3. Much of the limestone has eroded past the caves down to a layer of shale. Limestone peaks remain, many fractured with small, waterless caves.
Caves that open out into large halls filled with stunning limestone formations are found throughout karst areas. Minerals deposited by losing streams and water drainage create the strange shapes.
Fengcong karst, or peak-cluster karst, differ from the straight-sided fenglin. Their peaks are more cone-shaped and one hill meets the next across a depression or doline. Superb fengcong landscape can be seen near the small town of Xingping.
The Li River cuts through an impressive variety of karst hills. Cruises start in Guilin with fenglin, which gradually give way to dense fengcong.
Stone forests, such as Shi Lin outside Kunming, are karst formations created by the retreating waters of ancient seas, and wind and rain erosion.
Fenglin karst, which translates as peak-forest karst, is characterized by peaks that rise near vertically, like trees, 100 to 250 feet (30 to 80 m) above the surrounding flat floodplains. These dramatic tower-like karsts are found in and around the city of Guilin.
Caves that open out into large halls filled with stunning limestone formations are found throughout karst areas. Minerals deposited by losing streams and water drainage create the strange shapes.
Fengcong karst, or peak-cluster karst, differ from the straight-sided fenglin. Their peaks are more cone-shaped and one hill meets the next across a depression or doline. Superb fengcong landscape can be seen near the small town of Xingping.
The Li River cuts through an impressive variety of karst hills. Cruises start in Guilin with fenglin, which gradually give way to dense fengcong. from (http://www.chinaspree.com/china-travel-guide/china-guizhou-guangxi-tours.html )