YEHLIU GEOPARK

Rock formation Done By: 3E: Cherie Ko (7) 3D: Charlotte Ng (3) Ho Wen Xi (11) Shermaine Ling (19) Natalie Ng (21)

The name “Yehliu” was derived from: 1. A term translated from the Pinpu language 2. An abbreviation of the Spanish words “Punto Diablos (“devil’s cape”) 3. In early days, local residents earned their living at sea and they relied on rice suppliers from inner land to offer rice to them. During transportation, some local people would use the sharp bamboo tube to stick the rick sack and leave a hole on it, so that the rice may slip out and could be picked up by them. As a result, rice traders often mentioned “the rice was stolen by the savages” (whereas “steal” and “savage” are pronounced similar to Yeh (savage) and liu (steal) in Taiwanese).

INTRODUCTION

Yehliu is located at Wanli of Taipei County with a long cape.

Because the rock layer of nearby seashore contains limestone subject to sea erosion, weathering and earth movements, Yehliu is full of seawater-eroded holes as well as numerous rocks in the shape of mushroom, candle, ginger, and chessboard.

The rock landscape of Yehliu Geopark is one of most famous wonders in the world.

The costal line is stretching in a direction vertical to the layer and the structure line - besides, the influences caused by wave attack, rock weathering, earth movement and crustal movement all contribute to the formation of such a rare and stunning geological landscape.

Yehliu Geopark is divided into three areas, each containing different types of landform features.

Yehliu Geopark is famous for its sea-erosion landscape, while most of the spots are very close to the sea

INTRODUCTION

SIX DIFFERENT TYPES OF

LANDFORM FEATURES

1) Hoodoos

2) Pedestal Rocks

3) Ginger rocks

4) Honeycomb Rocks

5) Tafoni

6) Mushroom Rocks

ROCKS (PICUTRES OF THESE FORMATIONS)

1) Hoodoos 2) Pedestal Rocks 3) Ginger Rocks

4) Honeycomb Rocks 5) Tafoni 6) Mushroom Rocks

1) Hoodoos o Hoodoos typically form in areas where a thick layer of a relatively soft rock, such as mudstone, poorly cemented

sandstone or tuff (consolidated volcanic ash), is covered by a thin layer of hard rock, such as well-cemented sandstone, limestone or basalt.

o In glaciated mountainous valleys, the soft eroded material may be glacial till with the protective capstones being large boulders in the till.

o Over time, cracks in the resistant layer allow the much softer rock beneath to be eroded and washed away.

o Hoodoos are formed where a small cap of the resistant layer remains, and protects a cone of the underlying softer layer from erosion.

o Further erosion of the soft layer causes the cap to be undercut, eventually falling off, and the remaining cone is then quickly eroded.

o Typically, two weathering processes that continuously work together in eroding the edges of a rock formation form most hoodoos. The primary weathering force is frost wedging.

o In the winter, melting snow, in the form of water, seeps into the cracks and then freezes at night. When water freezes it expands by almost 10%, pries open the cracks bit by bit, making them even wider, much like the way in which a pothole forms in a paved road.

o In addition to frost wedging, rain also sculpts these hoodoos.

o In most places today, the rainwater is slightly acidic which allows the weak carbonic acid to slowly dissolve limestone grain by grain. It is this process that rounds the edges of hoodoos and gives them their lumpy and bulging profiles.

o Where internal mudstone and siltstone layers interrupt the limestone, you can expect the rock to be more resistant to the chemical weathering because of the comparative lack of limestone.

o Many of the more durable hoodoos are capped with a special kind of magnesium-rich limestone called dolomite. Dolomite, being fortified by the mineral magnesium, dissolves at a much slower rate, and consequently protects the weaker limestone underneath it.

GEOLOGICAL PROCESSES

2) Pedestal rock:

Two broken concretions within rock layers are formed vertical to the sea level; as a

result, the erosion caused by seawater may progress along the concretions, leading to the formation of stone pillar lining up in

row.

The formation of mushroom rock is caused by differential erosion as the top rock layer containing calcium and being more durable

for erosion than the lower rock layer.

The mushroom rock as formed is under continuous plate extrusion and thus is

raised above sea level. Once it’s exposed to the planet’s atmosphere, it will suffer from weathering as well as rain erosion and turn

into the shape as we see it now

3) Ginger rock:

Since the rock layer contains irregular concretions within, the harder concretions

may raise above the ground while the softer ones may descend downward as

erosion imposes upon the rock.

The surface of the hard concretion may become rough and uneven as it is exposed

to the atmosphere and having direct contact with the wind and the sea.

The interlacing patterns as shown on the surface of ginger rock are the result of crust extrusion occurred underground.

These patterns as shown are called “joints” in Geology.

GEOLOGICAL PROCESSES

4) Honeycomb rocks:

Honeycomb rock forms in three stages, and is caused by nodules composed of

organic detritus:

The rock is full of nodules composed of organic detritus, including debris from mollusks and sea urchins. As the rock

dissolves away, or crumbles due to the effect of weathering, the nodules

exposed on the surface are transformed into many small pits.

Salt from seawater continue to eat away at the rock, gradually expanding the small pits and forming the current

honeycomb shape.

5) Tafoni: Tafoni are small cave-like features found in

granular rock such as sandstone, with rounded entrances and smooth concave walls. They often occur in groups that can riddle a hillside, cliff, or other rock formation.

If the water is carrying salts - minerals dissolved in the water than can include sodium chloride but also a host of other chlorides, sulphates, and carbonates - then they will crystallize out as the water dries.

Crystallizing salts increase their volume as they form, which produces significant pressures between the grains, forcing the solid rock to crumble. The chemical and physical solidity of any rock is not uniform and some parts will be more vulnerable than others; the process continues through cycles of wetting and drying, chiseling, excavating, and smoothing.

GEOLOGICAL PROCESSES

6) Mushroom Rocks Two broken concretions within rock layers are formed vertical to the sea level, as a

result, the erosion caused by seawater may progress along the concretions, leading to the formation of stone pillar lining up in row.

The formation of mushroom rock is caused by differential erosion as the top rock layer containing calcium and being more durable for erosion than the lower rock layer.

The mushroom rock as formed is under continuous plate extrusion and thus is raised above sea level.

Once it’s exposed to the planet’s atmosphere, it will suffer from weathering as well as rain erosion and turn into the shape as we see it now.

The mushroom rocks can be divided into three types : “Thin-neck rock”,” thick-neck rock” and “neckless rock”. As many of the thin-neck mushroom rocks undertake heavier load on the top and they may be toppled down easily if striking by earthquake or violent winds and waves.

They may involve into neckless rock, thick rock, thin rock and even the broken-end rock eventually.

The top of the thin rock may fall apart if the neck of the rock contains incomplete sands and thud accelerating the formation of broken-end rock.

GEOLOGICAL PROCESSES

ROLE OF NATURE IN SHAPING THESE LANDFORMS

• Yehliu Geopark is a coastal area, and rocks are often subjected to erosion by seawater.

• It forms many different types of rocks such as elephant rocks, fairy shoe, earth rock and peanut rock.

• The rocks consist mainly of Sedimentary rocks, which results in the formation of sea bays due to sea erosion on softer rock layer

• Hard and solid rocks may turn into sea capes

ROLE OF NATURE IN SHAPING THESE LANDFORMS

• Weathering results and decomposition of earth rocks, rocks may turn into sand, mud and soils due to chemical changes of inner substances or physical functions such as heat expansion and cold contraction.

• Because of the influences of Northern monsoon which allows weathering to be detected.

• Formation of strange rocks due to the decomposition of special rock layer which exist underground

• Because of the erosion and weathering that many different and interesting types of rocks can be formed in that area. beautiful rock landscape

CREDITS / SOURCES

http://www.ylgeopark.org.tw/ENG/info/YlIntroduction_en.aspx

http://upload.wikimedia.org/wikipedia/commons/b/b8/SC02909_Panoramic_view_from_Yehliu_Geop

ark_in_Taiwan.jpg

http://www.thefoodpursuit.com/wp-content/gallery/taiwan/yehliu-geopark-mushroom-rocks.jpg

http://farm3.staticflickr.com/2523/4191229733_cabd4744e6_z.jpg

http://lh4.ggpht.com/-wRawmkDQwMs/TyFai3eXBVI/AAAAAAAACVw/Fn0Ks4pPoMM/Yehliu-

Geopark---Elephant-Rock_thumb.jpg?imgmax=800

http://lh5.ggpht.com/-arFFV2g_tIw/TyFalhld3_I/AAAAAAAACWU/691bhuBsEas/Yehliu---Peanut-

Rock_thumb.jpg?imgmax=800

http://www.ylgeopark.org.tw/ENG/landscape/Sight_en.aspx

http://www.flickr.com