Pennsylvanian- OK gesture (Wikipedia)
The OK gesture or OK sign or ring gesture (symbol/emoji: “👌”) is performed by joining the thumb and index finger in a circle, and holding the other fingers straight or relaxed away from the palm. Commonly used by scuba divers, it signifies “I am OK” or “Are you OK?” when underwater. In most English-speaking countries it denotes approval, agreement, and that all is well or “okay”. In other contexts or cultures, similar gestures may have different meanings including those that are negative, offensive, financial, numerical, devotional, political, or purely linguistic.
- Mississippian (geology) (Wikipedia)
The Mississippian (/ˌmɪsɪˈsɪpi.ən/ miss-ə-SIP-ee-ən, also known as Lower Carboniferous or Early Carboniferous) is a subperiod in the geologic timescale or a subsystem of the geologic record. It is the earlier of two subperiods of the Carboniferous period lasting from roughly 358.9 to 323.2 million years ago. As with most other geochronologic units, the rock beds that define the Mississippian are well identified, but the exact start and end dates are uncertain by a few million years. The Mississippian is so named because rocks with this age are exposed in the Mississippi Valley.