Landform & Geology
After millions of years, the streams of Taroko Gorge still tell the story of its formation. Both geological uplifting and erosion by the Liwu River have formed walls hundreds of meters high, a phenomenon seldom found elsewhere in the world. In addition, there are magnificent mountains, such as the pyramid-like Mt. Zhongyangjian, and the dramatic Qilai Mountain.
The Formation of Taroko Gorge
If we study the geological history of this area, it is not difficult to understand the origin of what we see today. Uplifting, followed by erosion by rivers, caused the formation of most of the geological features. The Liwu River, when newly formed, was not nearly as dramatic as it is today, but as time went on, the topographic variation became more pronounced. The island of Taiwan continued to rise, which caused the Liwu River to continue its erosion.
The formation of Taroko Gorge involved many steps:
- 1.Formation of limestoneBefore the existence of Taiwan, calcareous sediments were deposited in the ocean. As time passed, new sediment kept accumulating on top of the old; this, followed by lithification, formed limestone.
- 2.Limestone metamorphosed into marbleAfter the deposition of the limestone, layers of other materials were deposited, burying the limestone. After a long period of time, the intense pressure and subterranean heat caused the transformation of the limestone into marble.
- 3.Uplifting of marbleAbout seventy million years ago, the rock strata under the sea were forced up to form mountains, including the Taiwan mountain ranges. At the same time, the horizontal marble strata were also forced upright.
- 4.Further uplifting of marbleAbout four million years ago, the Philippine Sea Plate and the Eurasian Continental Plate collided, causing the mountains to rise up and the marble stratum, covered by other strata, to rise with them.
- 5.Valleys formed by river erosionDuring the millions of years that have passed, the action of rainwater and streams has eroded a massive amount of rock. At the same time, the continents have been rising, so the mountains have become higher and higher while the valleys have become deeper and deeper.
- 6.Formation of Taroko GorgeBecause the exposed marble was hard and resistant, it did not easily erode, so the resulting valley was narrow with very steep sides. This nearly vertical valley we call Taroko Gorge.