Sentinel Rock Overlook

Sentinel Rock Overlook. A Place Where Sandstone Beds Were Turned On End. The large outcrop with the staircase and cables is Sentinel Rock. The Civilian Conservation Corps (CCC) installed the steps and railings on Sentinel Rock sometime berween 1933 and 1942. It is now a popular climbing rock., One of the responses of the federal government to this country’s Great Depression was to create the CCC in 1933 and the Works Progress Administration (WPA) in 1935 to construct public works projects nationwide. With a great sense of pride, the country witnessed the CCC and the WPA building the nation’s infrastructure. They made major contributions to the development of state park facilities and helped restore and reconstruct historic sites., The CCC was instrumental in building many of the park’s roads, hiking trails, park residences, picnic tables and camping facilities. Of special significance is the stonework throughout the park, seen in culverts, retaining walls in the campground, and Diablo Stoves. Their main achievement here in Mount Diablo State Park was building the Summit Visitor Center., Today, over 70 years later, hundreds of CCC buildings, structures and landscape features are still in place and used in about 48 California State Parks., Sentinel Rock Overlook , A Place Where Sandstone Beds Were Turned on End, Sentinel Rock is made of the same sandstone that created the rugged landscape of nearby Rock City. The sandstone is made of small grains of mineralized quartz and feldspar derived from the eroding ancestral Sierra Nevada. The grains were then transported by rivers and ocean currents and deposited in an ancient sea that covered the area 45 to 50 million years ago. Those deposits eventually consolidated into thick layers of sandstone., During the uplift of Mount Diablo, the rocks in this area, originally horizontal, were turned upward 9 degrees. From this overlook, the rock layers can be viewed across the landscape. As you look from right to left the vertical beds become younger in age. Erosion has left the hardest layers standing upright as lone ridges and isolated pinnacles, such as Sentinel Rock.