Quaternary Meaning
The Quaternary is a subdivision of geologic time. It is the Quaternary Period that covers almost the last 2.6 million years up to the present day of the earth. The Quaternary, as well as the Tertiary Periods both together, form the Cenozoic Era.
The quaternary meaning can be understood by the below-given image:
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Quaternary Geography
The Quaternary is further subdivided into two epochs, the first is the Pleistocene which is up to about 11,700 years ago and the second is Holocene which is about 11,700 years ago to the present day. The Quaternary Period is one of the very extraordinary changes that took place in the global environment and also the period during which much of human evolution had taken place.
The Quaternary Period has also involved many dramatic climate changes in the planet, which has affected food resources and led to the extinction of many species. The period also saw the rise of a new predator that is known as man.
Climatic Conditions During the Quaternary Period
Scientists from all over the world have evidence of more than 60 periods of glacial expansion that was interspersed with briefer intervals of warmer temperatures. The entire Quaternary Period which also includes the present is referred to as an ice age because of the presence of at least one permanent ice sheet i.e. Antarctica. However, studies say that the Pleistocene Epoch was much drier and also colder as compared to the present time.
The glacial advancement varied between continents, but approximately 22,000 years ago, glaciers covered about 30 percent of the surface of the earth. In areas that are now Europe and North America, there existed huge grasslands known as the “mammoth steppes” and had a higher productivity rate with greater biomass than the modern grassland. The grasses were very dense and also highly nutritious. Whereas, winter snow cover was quite shallow.
Ascent of Man During the Quaternary Period
Homo erectus was the first-ever hominid species that widely used fire. There are two hypotheses about the species’ origin. The first hypothesis is that the species were initially originated in Africa and later dispersed throughout Eurasia, with the ability to exploit the colder regions using fire and tools. The second hypothesis claims that the Homo erectus migrated to Africa from the region of Eurasia. Excavations in Dmanisi, Republic of Georgia, have uncovered fossil evidence that Homo erectus species were successful hunters.
The existence of the Homo neanderthalensis was from about 200,000 years ago to about 30,000 years ago. Fossil evidence showed that the species lived in western Europe which also includes southern Great Britain, throughout central Europe and Ukraine, and as far south as Gibraltar and the Levant. However, Neanderthal fossils have not been found in Africa. Neanderthals were shorter as well as stockier than modern humans with longer, stronger hands and arms. They lived in shelters, made and wore clothing, and also used diverse tools made up of stone and bone.
According to the climatic conditions, there was a requirement for a heavy diet in animal protein so they were sophisticated hunters. A recent discovery indicates that they also cooked and ate plants. They buried their dead and made ornamental or symbolic objects. No earlier hominid species have been shown to practice any kind of behaviour that indicates the usage of language.
Evidence suggests that Homo sapiens originated in the continent of Africa and the oldest fossils of anatomically modern humans, found in Ethiopia which are approximately 195,000 years old. By 100,000 years ago they had dispersed as far north which is now known as modern Israel, but the oldest fossils of modern humans are also found farther north are only 40,000 to 60,000 years old. By this discovery, it is clear that Homo sapiens, as well as Homo neanderthalensis, were contemporaries for a time. Few dental evidence claims that H. sapiens matured later than Neanderthals. This suggests that a longer childhood led to more time for social development as well as transmission of knowledge and technology to new generations.
This might have led to the division of labour allowing all the females as well as the young to forage for more diverse food sources. Diversification in diet could have been a species advantage for the Homo sapiens when the climate cooled again. The most recent Neanderthal remains are approximately 28,000 years old. Homo sapiens weathered the drastic climate changes and continued to disperse throughout the Earth whereas the Neanderthals became extinct.
FAQs on Quaternary
1. What is the Quaternary Period in the geological time scale?
The Quaternary Period is the most recent geological period in the Cenozoic Era, beginning approximately 2.6 million years ago and extending to the present day. It is distinguished by a series of dramatic climate oscillations, known as glacial and interglacial periods (or Ice Ages), and is notably the period during which modern humans (Homo sapiens) evolved and spread across the planet.
2. What are the two epochs that make up the Quaternary Period?
The Quaternary Period is divided into two distinct epochs:
- The Pleistocene Epoch (2.6 million years ago to 11,700 years ago): Often called the 'Great Ice Age', this epoch was characterized by the repeated advance and retreat of continental glaciers. It witnessed the existence of large land mammals known as megafauna.
- The Holocene Epoch (11,700 years ago to the present): This is the current epoch, which began after the last major glacial period. It is marked by a more stable and warmer climate, which allowed for the development of human agriculture and civilization.
3. What were the characteristic animals (megafauna) of the Quaternary Period?
The Quaternary Period, particularly the Pleistocene Epoch, was dominated by large mammals known as megafauna, which were well-adapted to the cold. Notable examples include the woolly mammoth, mastodon, giant bison, woolly rhinoceros, saber-toothed cats, cave bears, and dire wolves. These large herbivores thrived on the vast, grassy steppes, while the carnivores preyed upon them.
4. How did the climate of the Quaternary Period enable human migration to the Americas?
During the glacial periods of the Quaternary, vast amounts of ocean water were locked up in continental ice sheets. This caused a significant drop in global sea levels, which exposed the Bering Land Bridge—a stretch of land connecting Siberia (Asia) and Alaska (North America). Following migrating herds of large animals, early humans (Homo sapiens) used this land bridge to cross into and populate the Americas between approximately 13,000 to 10,000 years ago.
5. Why is the Quaternary Period so significant for understanding Earth's current geography?
The Quaternary Period is fundamentally important because its events directly shaped our modern world. The repeated cycles of glaciation and melting carved many of the physical features we see today, such as U-shaped valleys, fjords, and the Great Lakes. These processes also determined the courses of major rivers, created fertile soil deposits, and established the coastlines and sea levels that define our continents.
6. How do scientists study the past climates of the Quaternary Period?
Scientists use several forms of proxy data to reconstruct Quaternary climates. Key methods include:
- Ice Cores: Drilled from glaciers in Antarctica and Greenland, these cores contain trapped air bubbles that reveal the composition of the ancient atmosphere.
- Ocean Sediments: Layers of sediment on the ocean floor contain the fossilised shells of tiny marine organisms, whose chemical makeup indicates past water temperatures.
- Pollen Analysis: Fossilised pollen grains preserved in lake beds and bogs show what types of plants were growing, indicating the regional climate at the time.
7. What caused the mass extinction of megafauna at the end of the Pleistocene epoch?
The extinction of megafauna like the woolly mammoth is attributed to a combination of two major factors. First, rapid climate change at the end of the last Ice Age caused glaciers to retreat and forests to replace the vast grasslands, drastically altering the animals' habitat and food supply. Second, the arrival of highly efficient human hunters placed significant new predatory pressure on these large animal populations. Most scientists believe this combination of environmental stress and overhunting led to their extinction.
