It crosses a section that is mostly desert, but is connected with the Bullfrog District by the Las Vegas & Tonopah, which runs from Goldfield through Beatty and Rhyolite, and meets the San Pedro, Los Angeles & Salt Lake at Las Vegas.
The volcanic series include the rhyolite of Nell Island, some obsidian, and the sheets of basalts which form the Cloudy Mountains, Mount Dayman and Mount Trafalgar (an active volcano), and also cover wide areas to the south and west of the Owen Stanley Range.
The Nahuatl lapidaries had at hand many varieties of workable and beautiful stone - onyx, marble, limestone, quartz and quartz crystal, granite, syenite, basalt, trachyte, rhyolite, diorite and obsidian, the best of material prepared for them by nature; while the Mayas had only limestone, and hard, tenacious rock with which to work it, and timber for burning lime.
Kachess rhyolite 02000
Augite-andesite predominates, but basalt and rhyolite also occur.
In the south of the island there are sills and dykes of felsite, quartz-porphyry, rhyolite, trachyte and pitchstone.
Quartz occurs as a primary and essential constituent of igneous rocks of acidic composition such as granite, quartz-porphyry and rhyolite, being embedded in these either as irregularly shaped masses or as porphyritic crystals.
The principal quarries are in Dodge, Green Lake (a blackish granite is quarried at Utley and a pinkish rhyolite at Berlin), Marathon, Marinette, Marquette, Sauk, Waupaca and Waushara counties.
- Recent volcanic eruptive rocks (including rhyolite, trachyte, phonolite, andesite and basalt) have been examined at a number of points throughout both the geological regions of the island.