Final answer:
The Tertiary Period is the older of the two periods, noted for its warm, humid climate and mammal evolution, while the Quaternary Period is marked by ice ages, glaciations, and a cooler climate. The last ice age ended about 14,000 years ago, leading to the current warmer inter-glacial period.
Step-by-step explanation:
The correct ordering of climatic time periods from oldest to youngest is the Tertiary Period followed by the Quaternary Period. The Tertiary Period, which lasted from 65 million years ago to 1.8 million years ago, was characterized by a generally warm and humid climate that allowed mammals to evolve and diversify. In contrast, the Quaternary Period, which began 1.8 million years ago and continues to the present day, has been marked by repeated ice ages with significant glaciation periods and a cooler climate overall.
During the Quaternary Period, the Earth experienced multiple ice ages, significantly impacting the global climate, sea levels, and the distribution of species, like the woolly mammoths which adapted to the colder conditions. The last ice age ended approximately 14,000 years ago and was followed by the current inter-glacial period with warming temperatures that melted the large ice sheets. Scientists study oxygen isotope and sea-level data to understand the past climate, particularly over the last 65 million years (the Cenozoic era).