New Maps Illuminate Monterey Bay Area Seafloor

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Six new sets of maps reveal the diverse and complex range of seafloor habitats along 130 kilometers (80 miles) of the central California coast from the Monterey Peninsula north to Pigeon Point. The publicly available maps can be used by a large stakeholder community to understand and manage California’s vast and valuable marine resources. 

Six new sets of maps reveal the diverse and complex range of seafloor habitats along 130 kilometers (80 miles) of the central California coast from the Monterey Peninsula north to Pigeon Point. The publicly available maps can be used by a large stakeholder community to understand and manage California’s vast and valuable marine resources. 

The new U.S. Geological Survey publications combine new and legacy data to reveal offshore bathymetry, habitats, geology and seafloor environments in stunningly high resolution. Environments range from the rugged granitic bedrock along the high-energy coasts of the Monterey Peninsula, to the bedrock reefs that form the world-class surfing point breaks on the Santa Cruz County coast, to the smooth sand and mud in a large delta bar at the mouth of the Salinas River, and to the steep walls and sinuous channels of one of the largest underwater canyon systems in the world.

Sam Johnson, the USGS project lead, notes, “The new high-resolution datasets and maps are stimulating research – scientists are excited. Our stakeholders like to say that you can't manage it, monitor it, or model it if you don't know what the ‘it’ is. Our seafloor mapping provides that important ‘it’ to the entire coastal community.”

Seamless onshore-offshore geologic maps incorporating subsurface data document the location and geometry of the San Gregorio fault, and show how different strands of the fault extend through Carmel Canyon, cross the continental shelf west of Santa Cruz and Davenport, and combine to uplift Año Nuevo State Park and Año Nuevo Island. A separate fault system to the east in Monterey Bay is part of an actively deforming wedge of the Earth’s crust caught between the converging San Andreas and San Gregorio faults. The six new sets of California maps are Offshore of Pigeon Point, Offshore of Scott Creek, Offshore of Santa Cruz, Offshore of Aptos, Offshore of Monterey Canyon and Vicinity, and Offshore of Monterey.

The new publications are the latest products of the California Seafloor and Coastal Mapping Program. Each of them includes 10 map sheets, a pamphlet, and a digital data catalog with web services. The web services are a new addition to these and all previous products in the map series, making it easier for people to find and use the digital data on a wide variety of devices, including smartphones. The maps and data have a large range of applications. They provide:

- A foundation for assessing marine protected areas and habitats, and for understanding how marine species such as bull kelp, rockfish, crabs, and sea otters use the seafloor.

- Baselines for monitoring coastal change and sea-level-rise impacts.

- Critical input data for modeling and mitigation of coastal flooding.

- A framework for understanding coastal erosion and developing regional sediment management plans.

- Contributions to earthquake and tsunami hazard assessments.

- More accurate data for safer navigation.

- Essential information for planning, siting, or removing offshore infrastructure. 

“These new seafloor maps – used in partnership with the USGS – will give us an additional tool to protect Californians, as well as fish and wildlife. The new maps will be used to analyze offshore faults and earthquake hazards. They will also help us identify sources of sand to replenish beaches – and will help establish a scientific baseline to track changes in habitat near shore over time.  This investment will pay off for Californians in ways that we cannot even imagine now,” said California’s Secretary for Natural Resources and OPC Chair John Laird.

California Seafloor and Coastal Mapping Program is a unique collaborative effort to comprehensively survey and map all of California's state waters. It is supported by the USGS, the California Ocean Protection Council, NOAA, California State University at Monterey Bay, Moss Landing Marine Laboratories, and other government, academic, and industry partners.

Bathymetry of Monterey Canyon and the Soquel Canyon tributary
Bathymetry of Monterey Canyon and the Soquel Canyon tributary — Monterey Canyon is one of the largest and deepest submarine canyons in the world, reaching depths of 1,520 m (5,000 ft) at the State Waters boundary. Upwelling through the canyon provides nutrients for the highly productive marine ecosystem of Monterey Bay. Excerpt from USGS California State Waters Map Series – Monterey Canyon and Vicinity Map Area, Sheet 1.
Geologic Map of Monterey Canyon and the Soquel Canyon tributary
Geologic Map of Monterey Canyon and the Soquel Canyon tributary — Seamless onshore-offshore Geologic Map of Monterey Canyon and the Soquel Canyon tributary, showing canyon meanders, steep canyon walls, submarine landslides, and fault zones. Excerpt from USGS California State Waters Map Series – Monterey Canyon and Vicinity Map Area, Sheet 10.

 

 

“Seafloor Character” map of the Santa Cruz Region
“Seafloor Character” map of the Santa Cruz Region — This is a type of habitat map that classifies the seafloor based on surface hardness and roughness. Such maps are used in various types of ecosystem assessments and seafloor zoning, such as delineation or monitoring of marine protected areas. Excerpt from USGS California State Waters Map Series – Offshore Santa Cruz Map Area, Sheet 5.
Monterey Peninsula onshore and offshore shaded-relief map
Monterey Peninsula onshore and offshore shaded-relief map — The offshore area includes the Carmel submarine canyon in the lower left-hand corner, an extensive rocky terrain west of the Monterey Peninsula (excellent habitats for rockfish and lingcod, sea otters, bull kelp, and other species), as well as relatively smooth seafloor draped by sediment north of the Monterey Peninsula, in southern Monterey Bay. Excerpt from USGS California State Waters Map Series – Offshore of Monterey Map Area, Sheet 2

 

Map of unconsolidated sediment thickness in Monterey Bay, excluding Monterey Canyon
Map of unconsolidated sediment thickness in Monterey Bay, excluding Monterey Canyon — There is a very large sediment deposit at the mouth of the Salinas River (blue and green colors), but otherwise the inner continental shelf is mostly underlain by bedrock (white) or has only a thin sediment cover (pink). The thickness of offshore sediment is an important factor in understanding and forecasting coastal erosion in this area, and in devising strategies for dealing with sea-level rise. Excerpt from USGS California State Waters Map Series – Offshore of Monterey Map Area, Sheet 9
Faults and earthquakes recorded from the Monterey Peninsula to Pigeon Point
Faults and earthquakes recorded from the Monterey Peninsula to Pigeon Point — Map of faults and earthquakes recorded from the Monterey Peninsula to Pigeon Point, including the new offshore mapping. The on-land San Andreas fault zone (SAFZ) and the offshore San Gregorio fault zone (SGFZ) are long, continuous, hazardous faults. Crustal deformation between these two fault zones results in several shorter faults and fractures, including the Monterey Bay fault zone (MBFZ). Excerpt from USGS California State Waters Map Series – Offshore of Monterey Map Area, Sheet 9