2013 北美西部行腳之五 : 帽子溪火山溶岩地道 2013 Westbound 5 : Hat Creek Subway Cave
根據美國農業部資料: [二萬年前, 拉森火山帽子溪附近地面裂隙流出大量溶岩。溶岩在流動的過程中, 上層暴露於空氣的溶岩開始冷却和凝結,而下層灼熱的溶岩繼續向前流動。最後, 灼熱的溶岩流走了, 下面就變成中空的地道。現在的出入口其實是部份地道天花塌陷而成的。] 地道內並無照明, 必須帶備手電筒或頭燈。地道並不深, 但內進不久即覺寒氣襲人, 宜带備薄衣一件。未知何故(也許太黑了), 相機”暗中”對照並不理想, 要拍照的話, 宜慢動作, 讓相機有足夠時間對焦。由於Lassen 火山公園降雪量大, 火山溶岩地道每年只在五月至十月開放。
US Agriculture Department info: [Geology – Less than 20,000 years ago the lava of the Hat Creek flow was discharged in Large volumes from a series of north-south fissures (cracks in the earth). This river of lava located near the town of Old Station, crawled northward 16 miles, covering the floor of Hat Creek Valley. While the top crust cooled and hardened, rivers of red-hot lava insulated by newly formed rock above, continued to flow. Eventually, the lava drained away, leaving tube-like caves, the entrance to cave formed by a partial collapse of the cave’s roof many years ago. Subway Cave is the largest accessible tube in the flow.]
上到地面後, 沿着小徑往回走, 可返回入口處。其實地上又熱又曬, 應該從地道走回去更佳, 笨!
After exiting the cave, we followed a trail on the ground back to the entrance. However, the dazzling sun was hot! We should have walked back to the entrance inside the subway !!