Time Periods

What are Time Periods?

Time Periods represent phases of earths geological and enviromental history as categorized by researchers over the last few hundred years. The Geologic Time Scale is hierarchical and contains eons, eras, epochs and ages. All of the Time Periods within the Gignos catalog fall within the Neogene and Quaternary Periods which span the last 23 million years up to the present.

While somewhat of an abstract construct Time Periods help us to categorize sites and specimens into broader geologic and environmental context that tell us about the world that the people lived in. 

The Quaternary

The Quaternary is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ago to the present. The Quaternary Period is divided into two epochs: the Pleistocene (2.58 million years ago to 11.7 thousand years ago) and the Holocene (11.7 thousand years ago to today, although a third epoch, the Anthropocene, has been proposed but is not yet officially recognized by the ICS).

The Quaternary Period is typically defined by the cyclic growth and decay of continental ice sheets and the associated climate and environmental changes that they caused.[1]

Neogene

The Neogene informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period 23.03 million years ago to the beginning of the present Quaternary Period 2.58 million years ago. The Neogene is sub-divided into two epochs, the earlier Miocene and the later Pliocene. Some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary. The term "Neogene" was coined in 1853 by the Austrian palaeontologist Moritz Hörnes (1815–1868).

During this period, mammals and birds continued to evolve into modern forms, while other groups of life remained relatively unchanged. The first humans (Homo habilis) appeared in Africa near the end of the period. Some continental movements took place, the most significant event being the connection of North and South America at the Isthmus of Panama, late in the Pliocene. This cut off the warm ocean currents from the Pacific to the Atlantic Ocean, leaving only the Gulf Stream to transfer heat to the Arctic Ocean. The global climate cooled considerably throughout the Neogene, culminating in a series of continental glaciations in the Quaternary Period that follows.[2]