Track classifications Q. What is an 'A' class line, or a 'Q' class line, etc.? The permanent way sections are classified by IR according to the maximum speed (or more precisely, the maximum speed proposed for the immediate future) that the tracks are capable of supporting.
Isle Royale and the Keweenaw Peninsula remained high ridges of volcanic basalt. The scraping and digging by the glaciers, followed by surface exposure of the hardest material, the metal, was followed by sluicing of the land by glacial meltwaters.
Olivine: Olivine, any member of a group of common magnesium, iron silicate minerals. Olivines are an important rock-forming mineral group. Magnesium-rich olivines are abundant in low-silica mafic and ultramafic igneous rocks and are believed to be the most abundant constituent of the Earth's upper mantle.
Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form". The original rock is subjected to heat (temperatures greater than 150 to 200 °C) and pressure (100 megapascals (1,000 bar) or more), causing profound physical or chemical change.