Green Head Island is the “Type Locality” to see a Late Precambrian marble that is about 750 million to 1.2 billion years old. Marble is a metamorphic rock created when limestone is subjected to heat and pressure causing it to transform and recrystallize. The limestone was once sediment on the floor of a warm shallow sea.
Precambrian is the name given to a very long period of geologic time. As the name suggests it is everything before the Cambrian Period, and encompasses the time from the formation of the Earth 4.6 billion years ago to the start of the Cambrian 542 million years ago. Four billion years is a long time and to call it all Precambrian simplifies a complex period of Earth history. In the 1800s fossils were one of the only tools to distinguish Precambrian from younger rocks. Cambrian rocks often contain abundant fossils such as trilobites. The first presumed Precambrian fossil was discovered in the 1860s and was part of an intense search for the first record of Precambrian life. This first discovery was discounted by the end of the 19th century. Meanwhile Saint John geologist George Matthew described a fossil in 1890, not far from Dominion Park. His identification of the stromatolite Archaeozoon acadiense has withstood scientific scrutiny and is now known as the first Precambrian stromatolite fossil described in scientific literature.