Llano Grande is a flat area among mountains in State of Mexico in Mexico. It is an old volcanic caldera. It is at latitude 19.9910661 degrees north, longitude 99.6458468 degrees west.Page 31, The Geology of Iztaccíhuatl Volcano and Adjacent Areas of the Sierra Nevada and Valley of Mexico,, Issue 219, By Graham T. NixonPage 66, Mexico's Volcanoes: A Climbing Guide, By R. J. Secor
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External links Google Earth view