GEOLOGY OF AZURE MOUNTAIN
Rocks on Azure
Mountain are composed of metamorphic gneiss (pronounced “nice”) that is
over 1 billion years old. The minerals composing the rocks are tan to
white feldspar, gray glassy quartz and black hornblende. You may also
see some red garnet and a green mineral called diopside. These are
metamorphic minerals, formed through heat and pressure of the original
sedimentary and igneous rocks that covered the area.  Temperatures
necessary to form these minerals were on the order of 600oC and
pressure was probably about 6 kilobars.The metamorphism was caused by the collision of two continental landmasses, which resulted in the formation an ancient mountain range, known at the Grenville Mountains. This mountain range may have been similar in size and scale to the current Himalayan Mountains, which resulted from the collision of India with Asia. After hundreds of millions of years of erosion all that is left of the Grenville Mountain range are its roots, the rocks you are walking upon on Azure Mountain, and elsewhere in the Adirondacks and northern New York.  To see evidence of
the most recent geologic event to affect Azure Mountain, walk northwest
along the ridgeline to the large boulder, known as a glacial erratic,
resting on the edge of the mountain. Untold dozens of people have
pushed against this rock to try to get it rolling downhill, to no
avail. It was transported by a glacier during the last ice age, and
left here as the glaciers retreated 10,000 to 12,000 years ago. It is a
testimonial to the strength of the glacial ice, estimated to have been
a mile thick in the Adirondack region, which carved the landscape of
the mountains.Rob Badger Associate Professor, Geology Department, SUNY Potsdam |