- The Pennsylvanian (/ˌpɛnsəlˈveɪni.ən/ pen-səl-VAYN-i-ən, also known as Upper Carboniferous or Late Carboniferous) is, on the ICS geologic timescale, the younger of two subperiods (or upper of two subsystems) of the Carboniferous Period. It lasted from roughly 323.2 million years ago to 298.9 million years ago. As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain by a few hundred thousand years. The Pennsylvanian is named after the U.S. state of Pennsylvania, where the coal-producing beds of this age are widespread.
- Great Slave Lake (Wikipedia)
Great Slave Lake is the second-largest lake in the Northwest Territories of Canada (after Great Bear Lake), the deepest lake in North America at 614 m (2,014 ft), and the tenth-largest lake in the world by area. It is 469 km (291 mi) long and 20 to 203 km (12 to 126 mi) wide. It covers an area of 27,200 km2 (10,500 sq mi) in the southern part of the territory. Its given volume ranges from 1,070 km3 (260 cu mi) to 1,580 km3 (380 cu mi) and up to 2,088 km3 (501 cu mi) making it the 10th or 12th largest by volume.