Little is known about the history of the oldest exposed rocks in the area due to extensive metamorphism; the rock has been pressure-cooked. This somber, gray, almost featureless crystalline complex is composed of originally sedimentary and igneous rocks with large quantities of quartz and feldspar mixed in. The original rocks were transformed to contorted schist and gneiss, making their original parentage almost unrecognizable. Radiometric dating gives an age of 1700 million years for the metamorphism, placing it in the early part of the Proterozoic eon.