日御碕の岩石
日御碕の海岸の地質は、縦に連なる断崖が特徴です。ここの岩石はドームの形をした貫入性の流紋岩でできており、1600万年前にマグマが冷えて形成されたものです。岩の内部は、溶岩が冷却されて形成された断面が不規則な五角形または六角形になっています。これらの断片は、柱状節理として知られ、柱の向きは溶岩が冷える面に垂直になることがわかっています。これらの節理に沿って岩は簡単に割れやすく、強い波の作用によって幾何学的な形ができあがったのです。
Title Rocks at Cape Hinomisaki
- Tottori
- Shimane
- Okayama
- Topic(s)：
- Historic Sites/Castle Ruins Nature/Ecology National Parks/Quasi-National Parks
- Medium/Media of Use：
- Interpretive Sign
- Text Length：
- ≤250 Words
- FY Prepared：
- 2018
- Associated Tourism Board：
- Daisen-Oki National Park
- Associated Address：
- Taishacho hinomisaki, Izumo-shi , Shimane
English
Rocks at Cape Hinomisaki
The geology of Cape Hinomisaki is characterized by jointed vertical cliffs. The rocks here consist mainly of dome-shaped rhyolite, an igneous rock that formed as magma cooled within the earth’s crust about 16 million years ago. The cross sections of these rocks show irregular pentagonal or hexagonal shaped columns that were formed by the gradual contraction of lava as it cooled. These geologic structures, known as columnar jointing, form perpendicular to the surface of the cooling lava. The rock breaks away more easily along these joints, and over the centuries the pounding waves have sculpted the columns into geometric shapes.
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