Taylor Black’s young steers are wearing an innovative tool that may soon be deployed at other West Marin ranches: GPS collars. Her goal, supported by a MALT grant, is to better guide grazing in the ridges and ravines of Blue Marble Acres, an agricultural incubator on Point Reyes-Petaluma Road. The collars create an electronic boundary using coordinates. As a cow approaches a boundary, the collar plays a short musical scale. If the cow crosses it,…