1969 Map of Alcalde Hills

About this map

The Alcalde Hills and Juniper Ridge define a landscape shaped by petroleum extraction and drainage during the late 1960s. This survey reveals a dense network of industrial infrastructure throughout the Oil Field on the eastern edge of the quadrangle, where numerous drill holes and oil sumps are connected by a grid of named routes like Tornado Avenue and Gale Avenue. The transition from the high, arid ridges of the Diablo Range down into the Coalinga Valley and Pleasant Valley is marked by isolated landmarks such as Sprague Cabin and Dodge Mill. These features, along with scattered water sources like Indian Springs and Salt Spring, suggest a history of seasonal ranching and prospecting that predates and eventually coexisted with the more intensive energy development of the 20th century. Major drainages including Los Gatos Creek and Coalmine Canyon cut deep into the hills, providing natural corridors for early roads and trails.