The Quaternary System is the most recent geological time period, spanning from about 2.6 million years ago to the present. It is divided into two epochs: the Pleistocene, characterized by repeated glacial cycles, and the Holocene, which began around 11,700 years ago and continues today. This period is marked by significant changes in climate, sea levels, and the evolution of various species, including humans. During the Quaternary, the Earth experienced major environmental shifts, leading to the extinction of many large mammals, such as the woolly mammoth and the saber-toothed cat. The development of human civilizations also took place during this time, with advancements in technology, agriculture, and social structures. The Quaternary System is crucial for understanding the Earth's recent history and the impact of climate change on ecosystems.