Which 2 periods were known for their ice ages?

Two major geological periods renowned for their extensive ice ages are: 1. **Cryogenian Period (Neoproterozoic Era, ~720 to 635 million years ago):** - **Snowball Earth Hypothesis:** During the Cryogenian, Earth experienced some of the most severe ice ages in its history, where ice sheets may have extended from the poles to the equator, enveloping the entire planet in ice. This extreme glaciation is often referred to as the "Snowball Earth" scenario. - **Glaciations:** There were at least two major glaciation events during this period—the Sturtian and the Marinoan glaciations—which had profound impacts on the planet's climate, sea levels, and the evolution of early life. 2. **Quaternary Period (Cenozoic Era, ~2.58 million years ago to present):** - **Current Ice Age:** The Quaternary is marked by the ongoing Ice Age, characterized by repeated cycles of glacial (cold) and interglacial (warm) periods. We are currently in an interglacial phase known as the Holocene. - **Glacial Cycles:** Significant advances and retreats of continental ice sheets, especially in the Northern Hemisphere (e.g., North America and Eurasia), have shaped much of the current landscape, influencing sea levels, climate patterns, and the distribution of flora and fauna. These two periods are pivotal in understanding Earth's climatic history, the evolution of life, and the dynamic processes shaping our planet's surface.