📌 簡介 Introduction
歡迎來到香港最東端的偏遠島嶼——東平洲。與香港大部分由火山花崗岩和凝灰岩構成的地貌不同，東平洲完全由獨特的沉積岩組成。這次將帶領大家探索形成該島著名岩層（常被稱為「頁岩」或「粉砂岩」薄層，本地俗稱「千層糕」）的沉積過程。
Welcome to Tung Ping Chau, the easternmost isolated island of Hong Kong. Unlike most of Hong Kong’s landscape, which is dominated by volcanic granites and tuffs, Tung Ping Chau is entirely made of unique sedimentary rocks. This EarthCache focuses on the sedimentary processes that created the island's famous rock formations, often called "shale" or "siltstone" laminates, known locally as the "Thousands-Layer Cake."
🧪 地質背景 Geological Background
這裡的岩石屬於平洲組，是香港最年輕的岩石，可追溯至早第三紀（約5500萬年前）。
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古老湖泊： 數千萬年前，這裡是一個位於半乾旱、炎熱氣候下的封閉式大型鹹水湖。
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季節性沉積： 在雨季，河流將微細的粉砂和泥沙沖入湖中；在旱季，湖水蒸發，礦物質濃縮。這種週期性的循環形成了非常薄的沉積層，稱為紋層（每層厚度通常小於 1 至 2 毫米）。
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成岩過程： 經過數百萬年的壓實和膠結作用，這些微細的泥沙最終變成了粉砂岩、燧石和鈣質頁岩。
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地殼抬升與侵蝕： 地殼運動使昔日的湖底輕微傾斜（約 10-20 度）。隨後，海浪的長期侵蝕雕刻出平坦的海蝕平台（如更樓石），讓這些美麗的岩層邊緣完美展露。
The rocks here belong to the Ping Chau Formation and are the youngest rocks in Hong Kong, dating back to the early Tertiary period (about 55 million years ago).
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The Ancient Lake: Millions of years ago, this area was a large, landlocked salt lake in a semi-arid, hot climate.
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Seasonal Deposition: During rainy seasons, streams washed fine silt and mud into the lake. In the dry seasons, water evaporated, and minerals concentrated. This repetitive cycle created very thin layers of sediment called laminations (each layer usually less than 1 to 2 mm thick).
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Sedimentary to Rock: Over millions of years, compaction and cementation turned these fine muds into siltstone, chert, and calcareous shale.
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Tectonic Uplift and Erosion: Earth movements tilted the lake bed slightly (by about 10-20 degrees). Coastal erosion by waves then carved out flat wave-cut platforms (such as Kang Lau Shek), revealing the beautifully exposed edges of the layers.
📋 Logging Tasks / Log 要求
要log found這個 EarthCache，請前往坐標處並回答以下問題。請勿將答案發表在log中。透過 geocaching.com 的訊息中心系統將答案發送給我後，你可以直接log found此藏寶，無需等待我的確認。如果你的答案有任何問題，我會通知你。
To log this EarthCache, please visit the coordinates and answer the following questions. Do not post the answers in your log. You can log this cache without waiting for my confirmation, but you must send me the answers at the same time, by the system of Message Center of geocaching.com. If there is a problem with your answers I will notify you.
Q1: Texture and Layers (紋理與層次)
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Look closely at a fresh break or exposed cross-section of the rock. Estimate the average thickness of a single individual "page/layer" (lamination). Are the layers uniform in color, or do they alternate?
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仔細觀察岩石露頭或斷面的紋理。估計單個「岩層/薄層」的平均厚度。這些岩層的顏色是一致的，還是呈現深淺相間？
Q2: Mineral Composition & Hardness (礦物成分與硬度)
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Pick up a small, loose piece of the rock from the ground (Do not break the bedrock!). Try to scratch it with your fingernail or a coin. Does it crumble easily like mud, or is it surprisingly hard? (Hint: The high concentration of silica/chert here affects its durability).
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從地上撿起一小塊掉落的岩石碎片（切勿破壞或敲擊原生岩床！）。嘗試用手指甲或硬幣去刮它。它會像乾泥土一樣容易碎掉，還是出奇地堅硬？（提示：當地高含量的二氧化矽/燧石會影響其硬度）。
Q3: Dipping Angle (岩層傾角)
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Observe the flat rock platforms along the shore. The layers are not perfectly horizontal. Look at the water line—estimate the angle (in degrees) at which the rock layers dip into the sea.
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觀察沿岸平坦的海蝕平台。這些岩層並非完全水平。對比海平面，估計這些岩層傾斜流入海中的角度（度數）。
Q4:
- Take a photo of yourself with Shale as the background, or another photo that can indicate your identity as a geocacher. This photo can be sent together with your answer or added to your log.
- 請以頁岩為背景拍一張你自己或其他能表明你藏寶者身分的照片。這張照片可以與答案一起發送給我，也可以添加到你的log中。
⚠️ Safety First / 安全至上:
Tung Ping Chau is only accessible by ferry (usually on weekends). Please check the ferry schedules carefully. The coastal rocks can be very slippery, sharp, and dangerous during high tide or rough sea conditions. Do not attempt to walk on the rocks if waves are crashing over them. Leave no trace — do not damage, chip, or remove any rock samples from this protected Geopark!
東平洲只能渡輪前往（通常在週末）。請務必仔細檢查渡輪時間表。在海水高潮或風浪較大時，海岸岩石會非常濕滑、鋒利且危險。如果海浪拍打岩石，切勿強行在前。請保持環境清潔——切勿破壞、鑿取或帶走這個受保護地質公園內的任何岩石樣本！