Invited post from Grace Allison, geologist at Tonto National Forest.
“The Mescal Limestone (above) is a part of the Apache Group which is approximately Neoproterozoic in age, or 1.2 Billion years old (Ba). This limestone formed from a shallow sea and was intruded with basalt and diabase (below) between 1.05 and 1.14 billion years ago. The Mescal Limestone metamorphosed, forming asbestos at the Philips Mine.” Grace Allison appears in this image. Photo credit: Chad Harrold.
Geologic Map of the SW part of the Tonto National Forest: http://repository.azgs.az.gov/uri_gin/azgs/dlio/1615
Photo Date: circa 2021
