Covering nearly every inch of the rail but the rail head, grease has accumulated on about a 15 foot section of rail at the lubricator pumps. The grease is used to protect the wheel and rail from wear caused by friction, which is especially high where there is rail curvature. A hydraulic pump which is activated by a trains wheels, applies the lubricant. It has to be just the right amount, because to much will get on top of the rail, and to little will not provide enough protection... This small substance keeps massive trains on track!
