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.
Performance bearings come in multiple sizes. For performance applications, often a 1X bearing can be used to add 0.001-inch additional clearance. A -1 bearing will reduce the clearance by 0.001-inch. When mixing shell halves for custom clearances, always place the thicker shell half in the loaded side of the housing. In the case of rod bearings, this would be in the connecting rod side. Over- and under-size bearings halves should only be used in conjunction with a standard bearing half. Never combine a +0.001 with a -0.001 half. If you think about it, pressure is just the indication of resistance to flow.