Coastal Geology & Highway One

California Geological Survey issued a series of interesting maps and reports about landslide probabilities throughout our state. Of course, Highway One in Big Sur is covered. This portion of the work of the CGS was prepared for the Highway Management Plan. From time to time, I will share some of what I discover about the geology and construction of Highway One. I hope to continue this series and create a new page where the history of the road can be expanded upon, as I explore and share my discoveries. Where quotes are shared, I will provide a link to the source of the quote.

“Highway 1 was constructed through this geologically diverse landscape in the 1930’s and opened in 1937. Parts of the Highway north of Big Sur follow the Old Coast Road, completed from Monterey to Big Sur by Monterey County in the 1880’s. Construction of the highway involved extensive excavations that utilized steam shovels and blasting. Fill was placed in minor canyons and bridges constructed across major canyons. The highway has a long history of landslides which have both landed on the highway and undermined the road bed. Road closures have been common, with long term closure mainly due to large landslides in years of heavy rainfall.” (http://www.conservation.ca.gov/cgs/rghm/landslides/SR_185/Documents/CT001mon%20Report.pdf)

For this first post, take a look at the following. The first is part of the landslide classification key

This second map is a general map of the Alder Creek Area. Though it is hard to read, Alder Creek is right there at the blue “8.”

That was so that you would recognize where Alder Creek is on the landslide map below, also where the “8” is.

Interesting, isn’t it? If you find these maps difficult to read, you can see and download the maps at this site: Geological & Landslide Maps of the Big Sur Coast