Correct Option
The correct option is Glacial and inter-glacial periods
Explanation
The Pleistoc is a geological time division within the Quaternary Period, spanning from approximately 2.58 million years ago to 11,700 years ago. It is widely known as the "Great Ice Age" due to the prevalence of extensive ice sheets covering large parts of the Earth's surface.
Option Analysis
- The formation of the ozone hole is Incorrect: The formation of the ozone hole is a modern atmospheric phenomenon observed primarily in the late 20th century, caused by anthropogenic chemicals like chlorofluorocarbons (CFCs). It is not associated with the geological timeline of the Pleistocene.
- Glacial and inter-glacial periods is Correct: The Pleistocene Epoch is characterized by repeated climatic cycles known as glacials (cold periods with ice sheet expansion) and inter-glacials (warmer periods with ice retreat). The Holocene epoch, which follows the Pleistocene, is the current inter-glacial period.
- The warmest period in earth's history is Incorrect: The Pleistocene was a relatively cold period in Earth's history. The warmest periods occurred much earlier, such as during the Paleocene-Eocene Thermal Maximum (PETM) or the Cretaceous Period.
- The disappearance of dinosaurs is Incorrect: The extinction of non-avian dinosaurs occurred at the end of the Cretaceous Period (Mesozoic Era), approximately 66 million years ago. This event predates the Pleistocene Epoch by tens of millions of years.
Key Takeaway
The Pleistoc is defined by significant global cooling and the alternation of glacial and inter-glacial cycles, shaping much of the Earth's current topography and biodiversity.