Cape D'Aguilar - Blow Hole EarthCache
Cape D'Aguilar - Blow Hole
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Cape D’Aguilar (also known as Hok Tsui) is located at the south-easterly tip of Hong Kong Island.
The geology of the area is relatively complex. However, a key feature is that the granodiorite (it is like granite with coarse grains, but the body has more dark minerals) is traversed by a number of rhyolite dykes (a type of volcanic rocks but dislike granite, it cools quickly and so crystals are difficult to form and been seen) and basalt dykes (or mafic dykes, which is a type of volcanic rocks forms by rapid cooling lava that is rich in magnesium and iron. It is usually grey to black and fine-grained). Wave action along this exposed section of coastline has eroded the complex rock pattern to produce an interesting range of coastal landforms, such as cliffs, headlands, sea caves, and sea arches.
At GZ you are standing in front of a large sea cave. The roof of this sea cave has been breached so that it is now a blowhole. A blowhole is narrow chamber in a sea cliff with an opening at the top. Strong waves funnel into the cave and sea water and spray are pushed upwards and then forced out through the relatively narrow opening in the roof.
The blowhole is large enough so that you can climb into it and enjoy a taste of salt and the reverberating sound of the wave and whirling pebbles. The blowhole is also known as the "Thunder Cave" locally.
Here are the requirements to log this Earthcache:-
1. Examine the rocks on the right slope of the blowhole and you will find two very distinct types of rock blended together. Describe their differences.
2. Read the geological map and try to determine how this cave was formed.
Email the answers to the owner. Do not post the answers in your log.
You may also post a photo of you and / or your GPS in front of the blowhole. This is optional.
Please also note that the sea area around Cape D'Aguilar is the unique Marine Reserve of Hong Kong. While it is freely accessible to public, you should observe all the applicable rules. In general, fishing, swimming, diving and collecting organisms are strictly prohibited. Visit the link here for details. (visit link)
There are other geological treasures to explore in the area, including the sea arch and the exposed dykes cutting crossing the granodiorite at the coastal area near a stone plaque 50m southwest of GZ that is laid to commemorate the establishment of the Marine Reserve.
A historical treasure in the area is the Lighthouse 158. Built in 1875, a white round stone tower adorned with fine masonry works at the base and archway, it was one of the oldest lighthouses in Hong Kong. It is also a Declared Monument of Hong Kong. More info can be found here. (visit link)
遊鶴咀洞
水退流捲千石響
潮進浪破萬花淘
閉目得聞雷音洞
回頭再賞一缐天
遠行人
Additional Hints
(Decrypt)
1. Pbzcner gur fvmr bs gur tenva, pelfgny sbezngvba naq gur pbybhe bs gur ebpxf.
2. Fghql gur trbybtvpny znc. Jurer vf gur TM?
Treasures
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