What is Historical Ecology?
Historical ecologists collect and analyze diverse historical documents to better understand past habitats and conditions. Insight into how and why landscapes have changed over time helps us illuminate physical processes needed to sustain environmental functions and highlight the best ways to protect and restore habitats.
The San Francisco Estuary Institute, leaders in this field, have wisely pointed out that historical ecology is not a blueprint for recreating the past. Rather, understanding the past helps us to plan for the future.
Elkhorn Slough Through Time
- 12,000 years ago / A Different Coastline
12,000 years ago, toward the end of the last ice age, Monterey Bay’s shoreline was farther west and Elkhorn Slough was a freshwater river. It was during this period that people first arrived and settled in the Monterey Bay area. This place would change as the climate changed and people managed the world around them.
- 8,000 years ago / Vast Estuaries
Over time, sea level rose, and tidal water covered large portions of the Salinas and Elkhorn valleys, creating extensive estuaries. Later, as sea level rise slowed, sediment filled in some of these large, open water areas. Salt marshes colonized the shores of Elkhorn Slough and many animals, from oysters to fish to mammals, made their home here.
- Early People
For thousands of years, the first people in Elkhorn Slough caught a variety of fish from nearby rivers and the estuary. Tidal areas were a source of clams, mussels, and oysters. People hunted in the water and on land, catching seals, sea lions, sea otters, rabbits, deer, and tule elk. Sometimes, they even took pronghorn antelope, grizzly bears, black bears, bobcats, badgers, and gray foxes. In the uplands, people managed plants and ecosystems, in part, by using fire.
- Late 1700s / The Spanish Arrive
In 1770, the Spanish arrived, setting up the Monterey Presidio and Carmel Mission. These were small settlements, but the changes they brought to local tribes and landscapes were enormous. One of the worst can be seen in the foreground of this 1791 drawing, with people whose families had lived in nearby villages for thousands of years being put to work by the Spanish. Among those who entered the Carmel Mission were people from Kalentaruk, centered around Elkhorn Slough and its sister estuaries between the Salinas and Pajaro Rivers.
More Historical Ecology
Retention of alluvial sediment in the tidal delta of a river draining a small, mountainous coastal watershed. 2019. Continental Shelf Research. Abstract only. For a full copy, email email@example.com.
Particle size characterization of historic sediment deposition from a closed estuarine lagoon, Central California. 2013. Estuarine Coastal and Shelf Science. Abstract only. For a full copy, email firstname.lastname@example.org.
These are talks given at public meetings and scientific conferences (click on “comments” to see speaker notes that make it easier to follow along).
Want to explore the history of Elkhorn Slough for yourself? Some organizations spend years collecting hundreds or thousands of historical sources to guide land management decisions (we did!), but you can begin to understand Elkhorn Slough’s past with just a few informative maps and aerials, easily accessible using the free Google Earth application.
We’ve already shared historical aerials with Google Earth, and those are embedded in the application. To find them, zoom into the Elkhorn Slough area, and then click the timeline button on the top toolbar (looks like a clock, with a green arrow pointing counterclockwise). That will let you see Elkhorn Slough and its watershed as it appeared in 1931, 1949, and 1971.
We’ve also made a few of our favorite North Monterey County historical maps compatible with Google Earth, too. Those are below. To use them, download the file, then double click the .kmz file once it is downloaded. That should prompt Google Earth to open and load the map.
A fun way to use these maps is to click on the map name in Google Earth’s “Places” window, then go just below that window and click the “adjust opacity” button. That brings up a slide-bar to the right that lets you fade the map in and out, so you can see the aerial below—like a time machine right on your screen.
.kmz Files Viewable in Google Earth
1854: U.S. Coast Survey of the coastline between the Pajaro River and Tembladero Slough. Elkhorn Slough is called “Estero Grande or Roadhous’ Slough.” (T00473L.kmz)
1857: U.S. survey of Rancho Bolsa de San Cayetano, located between the Pajaro River and Elkhorn Slough. Elkhorn Slough is called “Vallejo’s Slough.” (T1857sancayetano.kmz)
1898: A survey of upper Elkhorn Slough and the Carneros Rancho. Blue is water; brown is salt marsh; green is “sweetwater” marsh. (1898 carneros.kmz)
1906: A survey of the lakes and freshwater marshes that once existed between Castroville and Salinas. (1906_Hare_Lakes.kmz)
1909: U.S. Army survey of Elkhorn Slough and Moro Cojo Sloughs, with a sketch of a proposed harbor at Elkhorn. A different version of this harbor was constructed in 1946. (1909_MossLanding.kmz)
1910: U.S. Coast and Geodetic Survey returned to resurvey the area mapped in 1854 – download the 1854 map above and compare the two maps with the slide bar. (T473A_1910.kmz)
1919: A broader view of the lakes between Castroville and Salinas, including the plans to drain them through a canal and laterals. (1919_Hare_Lakes.kmz)