注意： 1. 入山申請是必要的，可在登山前30天線上網站申請。 2. 錐麓斷崖有實際的危險，請務必謹慎觀察與體驗這個地質寶。
Note：1. Applying permission for hiking is needed. It is open for applying 30 days before your hiking. Check this website for official apply. Check this blog for detailed applying. Or, you can check some package tour website. 2. Zhuilu Cliff is a spot with real falling danger. Be careful with observing the site and experiencing this earthcache.
錐麓斷崖
岩石的同質性讓錐麓斷崖相當獨特。整個錐麓斷崖像是個巨大石塊，這可能會影響到他的坡度。
錐麓斷崖位在太魯閣中。太魯閣聞名於峽谷景色，走在太魯閣峽谷底端可輕易觀察到垂直的峭壁。錐麓斷崖位在一段困難危險的步道尾端，約海拔八百公尺的高度，從錐麓斷崖看出去的景色與太魯閣常見的景色相當不同，在錐麓斷崖可以看到整個峽谷地景、懸崖岩層、與明顯的侵蝕作用。
這個地質寶要做什麼？
探索岩石的同質性與峽谷的發展階段。
錐麓的岩石
太魯閣峽谷的岩石主要為變質岩，包含大理岩、片麻岩、片岩、與其他。變質岩受到不同溫度與壓力條件影響，讓原來的岩石變質為不同的岩石。變質岩可以完全改變為不同顏色、質地、或是外觀。
葉理是在岩石中的纖維狀平面組織，常作為變質岩鑑定特徵的依據，依照變質岩的結構大致可以分為兩個類別，有葉理的變質岩與葉理不顯著的變質岩。
太魯閣的岩石很古老，可追溯至南澳造山運動與蓬萊造山運動，壯麗的太魯閣峽谷和一些因素相關，包含快速抬升、下蝕作用、變質岩(大理岩)的強度與脆弱性、與氣候變遷(閱讀GC6WE80獲得更多跟太魯閣峽谷有關的詳盡知識。)
錐麓岩石的同質性
錐麓斷崖的岩石大致具有同質性，主要為大理岩與片麻岩。這個特徵讓錐麓斷崖很獨特，河流侵蝕河道的岩壁，板塊抬升作用讓河流下蝕作用更強烈，另一方面，岩石的硬度則會阻礙拓寬的力量(側向侵蝕作用)。這些岩石硬度很高、不容易崩塌，且因為同質性的關係，所以不太會發生差異侵蝕。
詳見上方圖片所示，當(垂直或水平)地層為不同類群的岩石，差異侵蝕便有可能會發生，如果發生下方岩層受侵蝕作用較大的情況，上方岩層會失去支撐力，進而加速了侵蝕作用。
大理岩為高硬度且沒有明顯葉理的岩石，石灰石在高溫、高壓下變質為大理岩，大理岩的弱點是些微溶於碳酸水，大理岩的顏色主要是白色，有時候因為內含不同礦物而有不同顏色。片麻岩則是從花崗岩變質而來，具有中度至高度的葉理，片麻岩的顏色主要為黃色、棕色、與深灰色。
改變中的峽谷
根據峽谷的外型可區分為三種不同類型，分別為V型、U型、和平坦沖積型。不同類型的峽谷可區辨出氣候、環境、甚至是地景的發展階段。U型峽谷由冰川形成，V型與平坦沖積型由河流侵蝕作用而成形，V型峽谷還在年輕的發展階段，平坦沖積型則是完全被侵蝕與沈積為沖積平原。
站在錐麓斷崖可以俯瞰超乎尋常的峽谷與懸崖景色，峽谷的類型也可以從這個景色中一覽無遺，還有可能可以體驗地球表面的改變過程。
來走走這個步道抵達錐麓斷崖，與探索壯麗的地質景觀。
Uniqueness of Zhuilu Cliff
Rock's homogeneity makes the Zhuilu Cliff so unique. Whole Zhuilu Cliff is like a giant rock in a type of rock! This feature may affect the slope of the wall of the valley.
Zhuilu Cliff is inside Taroko. Taroko is famous for the gorge landform. It is easy to observe a nearly vertical cliff while walking in the bottom of Taroko Gorge. Zhuilu cliff is located at a height of eight-hundred meters, the end spot of a tough and dangerous hiking trail. Views from Zhuilu Cliff are so different from the usual sights of the Taroko gorge. Standing at Zhuilu Cliff, you can see the entire valley. The formation of the valley and the result of river erosion can be observed.
What to do with this earthcache?
Explore the homogeneity of rock and the formation stage of valley.
Rocks at Taroko
Main rock type in Taroko Gorge is metamorphic rock, mainly marble and some gneiss, schist and others. Metamorphic rocks are formed with different temperature and pressure conditions, and made the rock morphed different from the original rock. Metamorphic rocks can be totally changed into different color, texture, or appearance.
Foliation is a specific feature belongs to metamorphic rocks. The layering within metamorphic rocks is called foliation. The texture occurs when a rock is shortened during recrystallization. The structure of metamorphic rocks can be divided into two categories, foliated and non-foliated.
Rocks in Taroko are ancient. They were formed subjected to the Nanao Orogeny and Penglai Orogeny. Gorge Taroko is grandiose due to some factors, high rates of uplifting, down-cutting of erosion, strength and vulnerability of metamorphic rock (marble), and climate events (read GC6WE80 for detailed knowledge about the Gorge and valley).
Homogeneity of Rocks in Zhuilu
Rocks in Zhuilu Cliff are roughly homogeneous, mainly marble and gneiss. This feature made Zhuilu Cliff remarkable and different from the other section of cliffs in Taroko. Zhuilu Cliff is like a giant rock! River eroded the rock into the river channel. Uplifting of the plate may enforce the downcutting river erosion. On the other hand, the hardness of the rock may hinder the widening force of the erosion (lateral erosion). Their hardness is hard and not inclined to collapse. And differential erosion did not occur strongly due to homogeneity.
See the picture above for more detailed demostration. Differential erosion occurs when different rock type in (horizontal or vertical) layers. If the layers under were eroded quick, the upper layer would lose its supporting, accelerating the speed of erosion.
Marble is a type of rock with high hardness and without obvious foliation. Limestone under high pressure and heat may be metamorphosed into marble. Marble's vulnerability is more soluble to carbonated water. The color of marble here is mainly white and gray. It sometimes has other colors due to minerals. Gneiss may be derived from granite and medium-to-high foliation. The color of gneiss is yellow, brown, and deep gray.
A Changing in Valley's Shape
There are three different types of valley classified by their shapes, represented V shape, U shape, and Flat-floor shape. Different type of valley can indicate the climate, environment and even the stage of formation. U shape valley was formed with glacier. V shape valley and Flat-floor valley were formed with river erosion. V shape valleys were at their youth stage. Flat-floor valleys were thoroughly eroded and deposited with a floodplain. When a river runs, river erosion and deposition occurs at the same time. The process will continuingly change the surface of Earth. The landform is the state of equilibrium of the process. Reading the message from the state can tell the work of Earth.
Standing at Zhuilu Cliff can overlook the extraordinary gorge and cliff. The type of valley can be observed from the view. Moreover, it is possible to experience the formation process on the earth’s surface.
Let's hike the trail to Zhuilu Cliff and explore the grandiose geological landform.
登錄任務
岩石的同質性
1. 你有發現岩石的同質性嗎?不同高度懸崖的岩石都是同一種嗎?拜訪入口處、隧道一、隧道二、地質寶點(參見wayponit)，描述與觀察四個地點的岩石質地、顏色、葉理、和硬度。
2. 你會如何描述四個地點中岩石的組成百分比?(較多大理岩、較多片麻岩、或是其他類型的岩石)
3. 岩石的同質性會否影響峽谷橫切面的寬度或是縱切面的高度?比較四個地點的橫切面寬度、縱切面高度與形成你的想法。
改變中的峽谷
4. 錐麓斷崖的岩石很古老。觀察峽谷的形狀，你覺得峽谷處於什麼發展階段?(年輕還是古老) 峽谷和岩石一樣古老嗎? 解釋你的答案。
5. 預測錐麓斷崖這段太魯閣峽谷的未來變化，會不會變成平坦沖積型峽谷?解釋你的預測。
6. 請你、你的辨識物、你的GPS裝置與錐麓懸崖拍照。
線上登錄這個地質寶，請寄到Geocaching.com的信箱，若有什麼問題，會再回覆給你。除了登錄任務6，請不要在線上log中公佈你的答案，感謝。
Logging task
Homogeneous Rock
1. Do you find homogeneity of rock? Are rocks in the same type at different heights of the cliff? Visit the entrance, the tunnel I, the tunnel II, and posted coordination (see waypoints). Describe the color, texture, foliation or not and the hardness you observe in four spots.
2. How would you describe the proportion percentage of rocks in four spots? (More gneiss, more marble, or more other type of rocks)
3. Does homogeneity relate to the distance between the walls of the valley in a cross-section view? Or related to the height of the walls of the valley in a longitudinal section? Compare the distances and the height of the walls at four spots and make your theory.
A Changing in Valley's Shape
4. Rocks in Zhuilu Cliff are ancient. Observing the shape of the valley, how would you say the stage of the valley? (Youth or old) Does it as ancient as those rocks? Why or why not? Explain your answer.
5. Predict the changing of Taroko valley at the section of Zhuilu. Would it change into a Flat-floor shape valley? Explain your prediction.
6. Photo the Zhuilu Cliff with you, your identifying item, or your GPS device.
Log this cache "Found it" and send me your suggested answers either via my profile, or via geocaching.com (Message Center) messaging, and I will contact you if there is a problem. Don't post answers in the log except logging task 6, please.
Reference
Mountain and Valley
Valley Formation and Development
花蓮太魯閣峽谷地質簡介
Penglai Orogeny on Taiwan
太魯閣國家公園介紹