Unfortunately, it is not always clear what this layering tells us about a metamorphic rock's age and position in the stratigraphic stack. Layering in sedimentary rocks like brownstone is mainly a phenomenon of gravity. But the heat and immense pressure that cause metamorphism greatly alter the original gravity-induced layering in a rock, and sometimes create new layering. Old can become up and young can become down. These convolutions often make it impossible to apply the Law of Stratigraphic Succession to metamorphic rocks. In addition, fossils are rarely found in metamorphic rocks (and have never been found in metamorphic rocks from Connecticut). The process of metamorphism usually obliterates all traces of life that the original rock may have contained, erasing the tracks of time. Igneous rocks as well do not have fossils, except in very unusual circumstances. Radioactive dating is often the best hope for determining the age of metamorphic and igneous rocks, but this powerful technique can be applied only in special circumstances. Thus, placing metamorphic and igneous rocks in the stratigraphic column remains a difficult, and often controversial, task.

In Connecticut, much controversy has arisen from attempts to find a place in time for the metamorphic and igneous rocks. Although some controversy remains (and may always remain), the rough outlines of the stratigraphic column in Connecticut have emerged. Large sections of the column are not found in the rocks of Connecticut, which is not surprising when one considers how small Connecticut is. The missing portions do not mean that Connecticut had no geologic history during these gaps in the rock record; rather, they indicate that the geologic processes then acting on the state did not leave a record of rock - or if rock was left, that erosion has since carried it away. Unfortunately, the rock record is selective, seemingly capricious, and therefore offers incomplete evidence of the land's geologic history. Yet it is usually the only evidence.

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