Granite at the lookout in Gyro Park, has white bumps which are crystals of feldspar that give the rock a spotted appearance. A grey coating of lichen on the rock surface obscures much of the granite texture. The rectangular feldspar crystals contain amphibole and mica, the white is feldspar quartz . The large feldspar crystals weather more slowly than the finer-grained matrix and stand out in relief. Granite forms deep in the Earth when melted rock crystallizes slowly to a solid.
Volcanic Rocks
Most undeformed volcanic rocks were erupted from fissures and shield volcanoes Mechanical weathering of lavas and pyroclastic rocks proceeds in accordance with the arrangement of fracture planes. The presence of open vesicles or spaces left by gas bubbles in many lavas, gives additional opportunities for weathering attack. The physical weaknesses which augment mechanical disintegration also affect chemical weathering.
Along the trail to the lookout in Gyro Park is a dark green layered volcanic rock. The rock contains thin layers of different compositions that weather at different rates.It has a fine texture with an obvious directional grain (foliation),it contains thin layers of different compositions that weather at different rates which forms ribs on the rock surface. Silver, copper, and gold ores were discovered within volcanic rocks in the area. This volcanic rock is a green color due to impurities and diferent minerals in the rock which were altered by high temperatures and pressures while it was deep in the earth.This makes it a type of Metamorphic rock.
This is a 2 stage earth cache. The cords take you to the exposed volcanic rock and the next waypoint will take you to the viewpoint and the granite N 49° 29.781 W 117° 17.271 Please email the answers don't post them with your log
1) Estimate the height of the exposed rock at gz?
2) What direction is the layering going?(north/south, east/west)
3) Approx how big are the feldspar crystals on the granite?