Which period is characterized by numerous ice ages?

The Quaternary Period is characterized by numerous ice ages, marking significant climatic shifts and extensive glaciation events. This period, which began approximately 2.6 million years ago and continues to the present, is divided into two epochs: the Pleistocene and the Holocene. During the Pleistocene epoch, repeated glaciations occurred, with large ice sheets covering substantial parts of North America, Europe, and Asia.

These glacial and interglacial cycles had profound effects on the Earth's climate, sea levels, and the biogeography of species. The Quaternary is notable for the development of modern humans and the extinction of many large mammals, which were linked to the environmental changes brought about by these ice ages.

In contrast, the other periods listed do not have the same emphasis on ice ages. The Neogene Period primarily features the evolution of mammals and plants, the Cretaceous Period is known for the dominance of dinosaurs and the development of flowering plants, while the Paleogene Period also focused on the recovery and diversification of life following the extinction event at the end of the Cretaceous. Thus, the defining characteristic of ice ages is uniquely associated with the Quaternary Period.