Around 40% of land in Taoyuan Hsien is mountainous, mainly located in Da-shi Town and Fu-hsin Shiang. The mountainous area consists of the sedimentary rock of the Ga-li Mountains and metamorphic rock of the Sano Mountains.

Ga-li Mountains mainly consists of unaffected sedimentary rock including sandstone, shale, and clay. Igneous rocks are found in certain areas. The following areas are recommended sites to observe and enjoy the beauty of rocks:

	The roads of Shiao-wu-lai scenic sites: thick layers of sandstone often collapse after typhoons and heavy rains. Sandstone builds up to become tall mountains.
	Access roads to the forest recreational area of Tung-yen Mt.: various sedimentary rocks are found here, such as sandstone and shale. This area is an ideal spot to observe the contours of standard sandstone and shale
	Mountain along Bei-heng Highway between Jiao-ban Mt. and Gao-bo: huge sandstone, shale, and a mixture of both are found here

These sedimentary rock, such as the wave-like stipes and fossils, are solid evidence of the passage of time. When sediments precipitated, the sand was pushed by water and rolled forward along the bottom and wave-shaped stripes were created. Numerous wave-like stripes are found on the mountain along Bei-hen Highway nearby Sia-yin. These stripes tell us how the land at the bottom of sea rose to become mountains. The forest recreational area of Tung-yen Mt. has the largest number of fossils. Fossils are displayed at the tourist information center. There are also walkways to fossil areas.

The Snow mountain range mainly consists of metamorphic rocks created by mountain movement, such as metamorphic shale, metamorphic sandstone, and slate (the metamorphic rocks changed from shale and siltstone).

Metamorphic rocks can be seen along the North Cross-island Freeway south of Lung-hwa:

	Area of Lung-hwa Dam: Thin-striped metamorphic rocks are found along the roads. Hard sandstone and shale are found nearby Lung-hwa Dam. It is with these hard metamorphic rocks that Lung-hwa Dam was actually built
	Riverbed nearby Gao-yi: Huge black metamorphic rocks are found on both sides of the river.
	Between Ba-ling and Si-ling: As soon as you pass Ba-ling, you will see slate along Bei-heng highway. The slate has a smooth surface, and is the major construction material for aborigines living in the mountainous areas.
	Between Si-ling and Shen-yen: The hardest metamorphic rock in Taiwan Si-ling sandstone - is seen here. After metamorphication, minerals re-crystallized. If you dig out a piece of Si-ling sandstone and place it under sunlight, you'll see the shinny crystal minerals .

The wave-shaped bends created by movement of the mountain are known as folds. The folds curve in various ways, mainly upward (back sliding fold) and concave (forward sliding fold).

Folds can be seen in the following areas of Taoyuan Hsien:

	The area nearby Lung-hwa: The famous Chia-tien Mt. fold is located at the turn of the valley before Lung-hwa Dam. Looking afar from this fold, you'll see another back sliding fold in the remote mountain.
	Bei-chiao-tou of Ba-ling Bridge: There is a typical back sliding fold constituted by sandstone on the mountain to the right of the highway 100 meters away from Bei-chiao-tou of Ba-ling Bridge
	Scenic road to Shiao-wu-lai: As soon as you pass the entrance, you'll see the sandstone wall to the left of the highway. Take a close look, you'll see an arcing fold on the side of the mountain.