Background color for WARNING safety signs, labels, and tags. Marking hazardous parts of machines with may cut, crush, or otherwise injure. Emphasizing hazards when enclosure doors are open or when gear, belt, or other guards around moving equipment are opened or removed, exposing unguarded hazards. Marking exposed edges of
Bibcode:1995GBioC...9..377C. doi:10.1029/95GB01107. An ice age is a period of long-term reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers.
The Stone Age is also divided into three different periods. Paleolithic or Old Stone Age: from the first production of stone artefacts, about 2.5 million years ago, to the end of the last Ice Age, about 9,600 BCE. This is the longest Stone Age period. Remove Ads Advertisement.