Joe Carlin, Ph.D., assistant professor of geology at Cal State Fullerton, discussed his research of slowly changing landscapes on Earth and the effects that rising sea levels and coastal erosion caused by human activity could have on coastal habitats Tuesday at the latest OLLI talk, “Sands of Time.”
Carlin began his presentation with an overview of geological concepts, describing the effects of plate tectonics on the Earth’s landscape.
Mountains and other formations are created by the movement of these plates at a rate of about 4 centimeters a year, he said. These plate tectonics are the foundation of shape formation within the planet.
“That’s about the same rate as your fingernails grow,” Carlin said.
In his research, Carlin focuses primarily on the effects of plate tectonics and other factors on coastal areas. He tracks the geological history of these areas by collecting and analyzing sediments.
By unraveling the sediments of a location, one also unravels the geological history of that location, Carlin said.
Carlin and his fellow researchers survey the ocean by boat or walk through coastal marshes to collect sediment samples by sticking a tube in the sand and collecting sediments from the surface.
The process is like sticking a straw into a drink with a finger on top and collecting water within the straw, Carlin said.
After the sample is collected, it is taken back to the lab to be examined. Carlin compares this procedure to a holiday gift unraveling.
“It’s like Christmas every day you open it up. You never know what you’re going to see in there,” he said.
The sediment is run through instruments such as X-rays or CT scans to determine changes in density. These changes help ascertain the origin of the sediments, and how they got there, or changes within the environment.
Carlin spoke about his current research in Monterey Bay, where he has been working to determine the cause of excess sediment on the continental shelf.
He theorized that building dams along rivers has left sediment that has created a sandy area that protects bluffs from waves. When El Niño hits, the high waves erode cliffs and bluffs and that erosion could be the buildup of sediment.
This project illustrates something very important: “Humans are agents of geologic change,” Carlin said.
“The things we do to (the) coastal zone and the things we do to the watershed itself is going to impact the geologic record,” Carlin said.
Erosion will worsen by the rising sea level, which is an effect of global warming, Carlin said.
In future projects, Carlin plans to look at whether salt marshes along the coast are moving landward at the same rate as the sea level is rising. If they aren’t, this could mean the submersion of marshes and the reorganization of habitats, he said.