Rhyolite

Rhyolite is an igneous rock in the class designated as "felsic" rock. This class of rock crystallizes from silicate minerals at relatively low temperatures and with relatively a high percentage of silica . It is at the low temperature extreme of the Bowen reaction series.

花岗岩是一种酸性岩石。这类岩石是在较低温度下由硅酸盐矿物结晶形成的，且含有相对较高的二氧化硅含量。它处于 Bowen 反应系列的低温端。

Rhyolite has a composition similar to granite but has a much smaller grain size. It is composed of the light-colored silicates and is usually buff to pink in color. Occasionally it is light gray. In texture it is classified as aphanitic. It frequently contains voids and glassy fragments, evidence of having formed in a surface environment with rapid cooling. Rhyolite is much less common than granite, but there are large lava flows and deposits of rhyolite in Yellowstone Park, Wyoming, USA.

流纹岩的成分与花岗岩相似，但颗粒更细。它由浅色的硅酸盐组成，通常呈淡黄到粉红色，偶尔呈浅灰色。在结构上，它被归类为细粒的。它通常含有孔隙和玻璃质碎片，这表明它是在地表环境中快速冷却形成的。流纹岩比花岗岩少见，但在美国怀俄明州黄石公园有较大的熔岩流和流纹岩沉积物。

These rhyolite formations are along the Snake River in Hell's Canyon on the Idaho-Oregon border. The structures are referred to as "columnar jointing" and were the the most dramatic geologic features in appearance. There is much to be learned about geology in the canyon. It is like a time machine, which takes you back in history through several geologic eras.

这些流纹岩构造位于爱达荷-俄勒冈边境的地狱峡谷中的蛇河沿岸。这些构造被称为‘柱状节理’，在外观上是最重要的地质特征之一。峡谷中还有许多关于地质学的未知之处。它就像一台时间机器，带你穿越几个地质时代回溯历史。

The geologists on the trip referred to a study of Hell's Canyon by Tracy Vallier, "Islands and Rapids, a Geologic Story of Hell's Canyon." Vallier describes the areas where the columns occur as Permian rhyolite dikes. The columnar jointing is associated with lava flows and dikes of the Columbia River Basalt Group.

这次旅行中的地质学家引用了Tracy Vallier对Hell's Canyon的研究，题为《Islands and Rapids, a Geologic Story of Hell's Canyon》。Vallier将柱状节理出现的区域描述为Permian流纹岩岩墙。柱状节理与哥伦比亚河玄武岩群的熔岩流和岩墙有关。