11. The slopes of the peak are highly unstable, consisting of weak, hydrothermally altered felsic rocks . 12. The ages of these felsic rocks are generally between 2.5 and 3.8 billion years. 13. The chemical name of a felsic rock is given according to the TAS classification of Le Maitre ( 1975 ). 14. Continents must also be made up of less dense felsic rocks that " float " on underlying denser mafic rock. 15. The swarm consists of hundreds of dikes, filled with mafic to felsic rocks and are individually about in width. 16. For phaneritic felsic rocks , the QAPF diagram should be used, and a name given according to the granite nomenclature. 17. In addition, there are less dense felsic rocks in the western shore of the lake, which can contribute to the gravity low. 18. Exposed near a minor felsic lava dome is a fine grained, quartz-phyric felsic rock that may represent a rhyolite lava flow. 19. Augite is the most common ferro-magnesian in mafic rocks, but biotite and hornblende are on the whole more frequent in felsic rocks . 20. The darker soils, which support higher plant diversity, have developed on mafic rock; the medium-toned soils are on felsic rock .
