Quaternary Period: 65 Million Years Ago to The Present
The Quaternary Period is the current geologic period of the Cenozoic Era and extends from 2.6 Ma to the present. The Quaternary Period is subdivided into the Pleistocene and Holocene Epochs. Quaternary is derived from the Latin term for "by fours" quatern (Borror, 1988, p. 83). The Pleistocene Epoch is defined by repeated periods of glaciation. During this time intense periods of glaciation lasting up to 100,000 years alternated with warmer interglacial periods of 20,000 to 30,000 years (McNamara, 2009, p. 416). Continental glaciers during this time reached latitudes as far as 40 degrees. Many large mammals that flourished during this time went extinct at the end of the Pleistocene around 11, 700 years ago. The Holocene or present epoch represents an interglacial period. Fossils recognizable as human appear during the Quaternary Period.
Holocene
During the Holocene epoch, a wide array of plant taxa flourished. This included conifers like pine and cedar, deciduous trees such as oak and maple, various grasses-like wheat and rice, shrubs-like juniper and lavender, wetland plants such as cattails and reeds, and herbaceous plants like daisies and ferns. The plant composition varied based on factors like location, climate, and ecological conditions. The diverse plant life during the Holocene played a significant role in shaping ecosystems and supporting human development.
Pleistocene
A wide range of plant species existed during the Pleistocene epoch, which lasted from about 2.6 million to 11,700 years ago. The Pleistocene was marked by multiple ice ages and interglacial periods, resulting in varying climate conditions and significant changes in plant distribution. Conifers like pine, spruce, and fir were common throughout different regions. Deciduous trees like oak, maple, and beech were also prevalent, adapting to the changing seasons. Grasses played a crucial role in the landscape, providing food for herbivores. Wetland plants, including cattails and sedges, thrived in waterlogged areas, while various types of shrubs and herbaceous plants contributed to the overall biodiversity. The Pleistocene plant composition was influenced by environmental factors, including temperature fluctuations, glacial advances and retreats, and the interactions between plants, animals, and their habitats.
In addition to the diverse plant life during the Pleistocene epoch, there is evidence of petrified wood that has been preserved from this period.
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The petrified forest in Tak holds the Guinness World Record for having the longest known petrified wood 69.70 meters in length. The majority of them are canopy to emergent legume trees. These ancient wood remnants offer valuable insights into the flora that existed during the Pleistocene epoch and the geological history of the region.
References
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Borror, D.J. (1988). Dictionary of Word Roots and Combining Forms. California: Mayfield Publishing Company.
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McNamara, K. (2009). Quaternary Introduction. In Guerrero, A.G. & Frances P. [Eds]. Prehistoric Life: The Definitive Visual History of Life on Earth. New York: Dorling Kindersley.