The volcanic creation of the Canadian Shield took place during the Earthâs earliest geologic era, the Precambrian, which includes the earliest 80% of Earthâs existence. The Precambrian era ranges from about 5 billion to 570 million years ago.This process continues today in such places as Hawaii.he volcanic creation of the Canadian Shield took place during the Earthâs earliest geologic era, the Precambrian, which includes the earliest 80% of Earthâs existence. The Precambrian era ranges from about 5 billion to 570 million years ago.
608 STANDARD. The most common bearing size is the â608.â Characterized by an 8mm core, a 22mm outer diameter and a 7mm width, these bearings are the industry standard and match up with nearly every skate wheel out there. NON-STANDARD Of course, there are exceptions to every rule.
Unlike bearings, bearing spacers are not one-size-fits-all. Bearing spacer size is measured by two things: axle diameter (not to be confused with axle width!) and overall spacer width. For example, 8mm x 10mm is a very common bearing spacer size. The first number (8mm) refers to the diameter of the axle, and the second number (10mm) refers to the overall width of the bearing.