Paleolandscapes and the ca. 8,000 BP Shoreline of the Gulf of Mexico Outer Continental Shelf 2020

Past Expedition

Dates

June 2020

Location

Gulf of Mexico/Caribbean

Overview

In 2019, our project team spent two weeks offshore in the Gulf of Mexico collecting data to help us answer questions about areas of the continental shelf that were once exposed as dry land. Throughout time, global sea level has risen and fallen, alternately covering and exposing the land. Today, the Gulf of Mexico is largely known for its shrimping, fishing, and extensive offshore oil and gas development, but evidence of the earliest Gulf coast inhabitants could be preserved, buried under sediment and sea. But on a continental shelf where approximately 40 million acres could have been dry land in the last 12,000 years, where do you start looking?

Dr. Amanda Evans in the ship’s lab writing field notes on each core sample.

The Field Technician’s Awe

There was always a rush of wonder as we waited very patiently for the piston core to reemerge with our mud samples.

October 9, 2020

Sediment from the core catcher contained wood fragments, which were rinsed and catalogued.

Mission Update

We’ve completed sampling at four of our planned six locations and are now waiting on the weather to clear up so we can get back to work. After a productive first few days of coring operations, we were running ahead of schedule—then the seas picked up on us.

June 23, 2020

Amanda Evans (left) and Megan Metcalfe (right) monitor acquisition of the parametric sonar data onboard the R/V Nikola during fieldwork in 2019.

The Use of Sub-bottom Profilers in the Hunt for Submerged Landscapes

When looking for submerged landscapes below the seafloor, the main geophysical tool we use is a sub-bottom profiler. It can also show where there is a major change in angle and character of deposits, such as the cut of an ancient river channel, which has been filled by mud and sands.

June 18, 2020

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A split core, recovered in 2010, shows the transition from modern marine sediment (top right), through the Pleistocene clay (lower left).

Mission Plan

In 2019, our project team spent two weeks offshore in the Gulf of Mexico collecting data to help us answer questions about areas of the continental shelf that were once exposed as dry land. Throughout time, global sea level has risen and fallen, alternately covering and exposing the land. Today, the Gulf of Mexico is largely known for its shrimping, fishing, and extensive offshore oil and gas development, but evidence of the earliest Gulf coast inhabitants could be preserved, buried under sediment and sea. But on a continental shelf where approximately 40 million acres could have been dry land in the last 12,000 years, where do you start looking?

June 18, 2020

A shipwreck in 80 feet of water in the northwestern Gulf of Mexico was imaged using side-scan sonar (left); photographs taken by divers of the same wreck were obscured by lack of light and sediment in the water column (right).

Remote Sensing

How do you look for something that doesn’t want to be found? Since the river valleys and channels aren’t visible to the naked eye, we use different remote-sensing tools to image them.

June 18, 2020