Post Number: 3
|Posted on Sunday, August 20, 2017 - 6:54 pm: ||
I've seen reference on maps and in discussions elsewhere (Killarney) about acid rain being the cause of the acidification of lakes in this region. Consider this: that nearly all of all of the so-called "windex" lakes are underlain by a rock type known as quartz arenite - a very white sandstone made entirely of quartz sand grains. Such rocks are quite acidic to start with and thus have no buffering capacity, so waters flowing through and over them remain acidic. For those interested, the white rock in Lady Evelyn-Smoothwater area and Killarney is known as the Lorrain Formation (Maple Mtn, and Ishpatina Ridge are made of it). A set of very good geology maps of the Temagami region was published in 1973 by the Ontario Division of Mines "Geology of the Maple Mountain area" by K.D. Card, W.H McIlwaine and H.D. Meyn; Geological Report 106, 133 p., including 5 coloured maps. Likely out of print now but I'm sure one could get a copy from a university library or the Ontario Geological Survey, in Sudbury.
Post Number: 1847
|Posted on Monday, August 21, 2017 - 8:42 am: ||
Is this rock also called quartzite?
Post Number: 4
|Posted on Monday, August 21, 2017 - 8:51 pm: ||
Yes, but to a geologist, quartzite is the metamorphic (recrystallized) equivalent of a quartz arenite. The Lorrain Formation in Killarney is more of a quartzite whereas the Lorrain Formation in Temagami is still a sandstone (less affected by heat and pressure). These rocks are about 2.3 billion years old!