Arroyo Seco Canyon

Have you ever seen what the flanks of a 23million-year-old volcano look like after having traveled hundreds of kilometers along the San Andreas Fault? If not, it is imperative that you read more! The trip begins in the Salinas Valley, and takes you south to the actively eroding Arroyo Seco canyon, and then across the valley to the Pinnacles National Monument. The dynamic relationship between depositional, erosional, and tectonic processes of ancient and modern environments are exemplified by this beautifully rugged landscape.

Point Lobos State Reserve

Point Lobos State Reserve is conveniently located just off Highway 1 south of Carmel Valley. The two main geologic highlights of this area are the Eocene turbidites of the Carmelo Formation and the unique granodiorite porphyries of the Monterey Mass. The uplifted submarine canyon deposits of the Carmelo Formation provide a glimpse into the past as well as clues to the depositional processes now occurring in the nearby Monterey submarine canyon.

Santa Cruz Coastline

Tucked into the northern part of Monterey Bay is the town of Santa Cruz. It is known for its generally mild, Mediterranean-like climate, laid back lifestyle, excellent surfing, well-developed marine terraces, and beautiful coastline. Not only is the Santa Cruz coastline an excellent area to study the marine geology of the past, but it is an excellent area to study how coastal processes effect humans and vice versa. For instance, retreating cliff faces at Capitola Beachand riprap-protected cliffs at Steamer Lane provide dramatic examples of the constant pressure exerted by waves along this coastline. These formations represent two different marine depositional environments that offer clues about oceanographic conditions, marine life, and sea level changes of the past.

Santa Lucia Range

The Big Sur coastline is one of the most spectacular coastlines in the United States, with amazing views, uncrowded beaches, and hairpin turns along Highway 1. This area owes much of its beauty to the tectonics of the region. Rapid uplift along thrust faults, such as the Sur-Nacimiento Fault, is responsible for the steep cliffs and partially-formed marine terraces that you will see on this tour. The dynamic up and down movement associated with these thrust faults has also created basins in which Paleocene marine sedimentary deposits, such as those found in the Indians Ranch, have been uniquely preserved.

Fremont Peak State Park

Want some perspective on the sequence of sea level changes and tectonic forces that shaped the Monterey Bay region? Then make an excursion up to Fremont Peak, on the north side of the Salinas Valley for a panoramic view of prominent formations. From the top of the peak you will see the Sierra de Salinas, the Santa Lucia and Santa Cruz mountains, Pleistocene dunes near Fort Ord, the San Andreas Fault and more. The white rocks exposed and scattered about on Fremont Peak are marble remains of a Jurassic seafloor, and beneath that is a mass of granite from the late Cretaceous (65 mya). How can an older formation be on top of a younger one? The granite pushed up from beneath, baked limestones into marble, and uplifted older layers. Eventually, they eroded from the hillsides leaving characteristic “roof pendants” sitting like caps on the mountains. The Oligocene Pinecate Formation is exposed in several road cuts on San Juan Canyon Road. This massive arkosic sandstone bed is orange to buff-yellow or brown and interbedded with a conglomerate of volcanics, carbonates and weathered granites. According to Clark and Reitman (1973), this was a shallow marine deposit with a proximal source to the west. The Zayante/Vergles fault is visible in eroded areas.