Sylvan is in the western tier of townships, within one of the southern line, and is numbered 18 north, of range 7 west. Middle Branch is on the north, Clare County on the east, Orient on the south, and Osceola Township on the west. The surface of the country is undulating, and in some parts quite broken, with a mixture of clay, sandy and loamy soil. It is exceedingly well watered, having the great Muskegon River, which comes in at the northeast corner of the township and, running in an oblique course, passes out near the southwest corner, the Middle Branch, which empties into the Muskegon, and several other large streams.