- Permian (Wikipedia)
The Permian (/ˈpɜːrmi.ən/ PUR-mee-ən) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period 298.9 million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the last period of the Paleozoic Era; the following Triassic Period belongs to the Mesozoic Era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the region of Perm in Russia.
- Tau (Wikipedia)
Tau /ˈtɔː, ˈtaʊ/ (uppercase Τ, lowercase τ, or τ; Greek: ταυ [taf]) is the 19th letter of the Greek alphabet, representing the voiceless dental or alveolar plosive IPA: [t]. In the system of Greek numerals, it has a value of 300.