Ramona Grasslands County Preserve
The Ramona Grasslands County Preserve encompasses 3,521-acres located near the town of Ramona in central San Diego County (Figure 1). The landscape that includes the preserve is part of the broad Santa Maria Valley, a highland valley with low relief that stands out in topographic contrast to the surrounding mountainous uplands and mesas of the surrounding Peninsular Ranges.

Only the southwest section of the preserve is open to the public. That section has trails for hiking, cycling, and horseback riding (Figures 2 and 3). The area is very popular for bird watching and wildflowers in season.

The preserve contains several miles of Santa Maria Creek and supports a mosaic of habitats including grasslands, coastal sage scrub, chaparral, oak woodlands, riparian woodlands, marsh/wetlands, and vernal pools. These habitats support with hundreds of unique plant and animal species (Figures 4 and 5).

Most of the of the preserve is inaccessible. It has been set aside is a conservation area for wildlife protection and requires a special permit is required for access. Limited cattle are permitted to graze in parts of the preserve.

Ramona Grasslands County Preserve (County of San Diego, Parks an Recreation website)

Click on images for a larger view.
Map of the hiking trails and vegetation communities in the Ramoa Grasslands County Preserve.
Fig. 1. Map of the hiking trails in the Ramona Grasslands County Preserve (in an area open to the public).
View of a grasslands field with a trail, a large oak tree, and a parking area in the distant center ofthe image.
Fig. 2. View of the Ramona Grasslands in the vicinity of the parking area on Highland Valley Road.		 View of a well maintained and partially fenced trail extending off into the distance at the Ramona Grasslands Preserve.
Fig. 3. View along the well-maintained Meadow Loop Trail in the Ramona Grasslands Preserve.		 Riparian woodlands habitat stands out as a curving line across the Ramona Graslands. Coastal Sage Scrub habitat is in the foreground. Forest covered mountains are in the distance.
Fig. 4. Riparian woodlands follow Santa Maria Creek where it drains across the Ramona Grasslands Preserve.		 View of an oak forest wis sime grasslands and sage scrib and wetland habitats in the Ramona Grasslands Preserve.
Fig. 5. Oak forest, coastal sage scrub and wetlands habitats in the Ramona Grasslands.

Bedrock Geology

Scattered throughout the broad valley are small inselbergs and knockers (boulder piles and outcrops) consisting of granite (Figures 6 to 9). These granite outcrops are evidence of the ancient Cordilleran volcanic mountain range that extended along the west coast (Alaska to Mexico) That was most active during part of Cretaceous Period, roughly 100 to 70 million years ago. The ancient volcanic mountains eroded away long ago as the landscape wore down to a broad coastal plain to a region of very low relief by middle Tertiary time about 40-30 million years ago. After that, changes in the plate tectonic setting of the region changes as "new" mountains and uplifted plateaus of the Peninsular Ranges began to rise. These mountains and plateaus are erosionally dissected crustal blocks that have been uplifted since the major fault systems in the region formed or became reactivated (including the San Andreas, Elsinore, and other regional fault). See Geology and Natural History of San Pasqual Valley for more information about the regional geologic history and formation of the highland valleys and plateaus.
Flat grass-covered fields with small granite outcrop areas histing scattered oak trees.
Fig. 6. Inselbergs (isolated granite outcrops) scattered across the grasslands.		 A large free-standing granite bouled wish other boulders in the grasslands.
Fig. 7. Granite knocker in the Ramona Grasslands near the parking area.		 A large outcrop of fracture granite exposed on a slope in the grasslands.
Fig. 8. Granite outcrop in the Ramona Grasslands.

 A grassy slope that extends along the margen of a large field of granite boulders with some oak trees.
Fig. 9. Granite boulders and outcrops in the Ramona Grasslands.
Several mountain peaks rise in a row along mountain fron with a slope covered with chaparral and coastal sage scrub in the foreground. Woodson Mountain has radio towers on its peak.
Fig. 10. Fault-bounded mountain front along Woodson Mountain, south of the preserve.		 View looking east over the Ramona Grasslands with the high peaks of the Cuyamaca Mountains in the distance. Coastal sage scrub habitat in the foreground.
Fig. 11. High Peaks of the Cuyamaca Mountains in the Peninsular Ranges east of Ramona.		 View looking north over the Ramona Grasslands with the high ridgelines of Mesa Grande and Palomar Mountain in the distance. Coastal sage scrub habitat and oak forest in the foreground.
Fig. 12. Long ridgeline of Palomar Mountain with Mesa Grande northeast of the Ramona Grasslands.		 View looking west from the hillsides covered with Coastal Sage Scrub habitat with the peaks of Franks Peak and Mount Whitney near San Marcos in the distance.
Fig. 13. Franks Peak (left) and Mt. Whitney (right) in the Double Peak area west of the Ramona near San Marcos.
The Ramona Grasslands and Santa Maria valley are part of the "Area of High Plateaus" physiographic region of San Diego County. In middle Tertiary time, rivers drained from the volcanic highlands of what is now the Sonora region of northern Mexico. These rivers flowed westward into the Pacific Ocean until the San Andreas Fault system began to develop along with the opening of the Gulf of California. Traces of these ancient rivers are preserved as isolated pockets of ancient river gravels found on the ancient surfaces and stream terraces still preserved on of some of the plateaus. Rounded cobbles of porphyritic andesite and rhyolite can be found reworked into the local soil and alluvial deposits (Figure 14).

It is important to understand that wildfire is part of the natural erosion processes that the created the landscape. As plants grow that help break down the bedrock as roots penetrate fracture in the bedrock, and the decay of organic residues introduce acids to the groundwater that weathers rocks into sediment and soil. Every few decades, a wildfire would burn across the landscape. The locally intense heat scorches both rock and soil. Trapped moisture and in the rock expand and contributing to breaking of exposed surfaces. Figure 15 shows the bright red patina of red hematite on blocks of granite that have experience intense heat of past wildfire.

Other than a period of cattle ranching, the Ramona Grasslands are a remarkable well preserved landscape. Limited cattle access to parts of preserve continues to this day as part of the preserve's rangeland management.
A patch of river terrace gravel exposed in the soil near the parking area at the Ramona Grasslands Preserve.
Fig. 14. Isolated pockets of ancient Sonoran river gravels.		 Blocky pink granite boulders with some covered with a red hematite patina.
Fig. 15. Fire-scorched granite with a patina of red hematite.		 A muddy small stock pond surrounded by forest with the top of Woodson Mountain in the distance.
Fig. 16. Old stock pond in the Ramona Grasslands Preserve.		 A Black Angus cow near the trail in the Ramona Grasslands.
Fig. 17. Black Angus in the Ramona Grasslands Preserve.
Panoramic view looking east of the plains of the Ramona Grasslands Preserve with the high peaks and ridgelines of the Peninsular Ranges in the distance.
Fig. 18. Panoramic view of the Ramona Grasslands County Preserve showing the high peaks and plateaus of the Peninsular Ranges in the distance. North is to the left; south is to the right; east is near the center of the image (Julian is in the distant skyline region near the center of the image, about 10 miles away).
https://gotbooks.miracosta.edu/fieldtrips/Ramona_Grasslands/index.html
 5/9/2022