Where is your current work focused?
My current work focuses on describing coastlines and looking for tsunami deposits all over the world. I continue to work in the Mediterranean and am also searching along coastlines of the Pacific and Atlantic Oceans.
Tsunamis are large and powerful ocean waves that grow in size as they reach the shore. Most are caused by earthquakes. When this happens underwater, big gaps may appear on the ocean floor. When water moves in to fill this gap, a tsunami forms. Tsunamis can cause major damage as they rush inland, flooding cities.
One of Goodman’s areas of study early in her career was the ancient coastal city of Caesarea in Israel. It was built by King Herod almost 2,000 years ago.
a beach in Caesarea, Israel
underwater ruins in Caesarea
Describe your first dive at Caesarea.
One of the excavation leaders took us out for a tour of the site. He wanted to check how all of our gear was functioning as well as see how well we could handle ourselves before the excavations began a few days later. I was, by far, the least-experienced diver in the group, so I was very nervous. However, as soon as we dropped into the water and were surrounded by massive blocks of ancient buildings, I was too distracted by all the things to see to even think about whether or not I was a good enough diver.
We cruised around the ancient cement blocks, now covered in marine plants and critters. At one point, they led us through a space between the blocks that felt like a small canyon. It felt a little too tight! But at the very bottom of that narrow space, our guide fanned the sand away from the block, and we could see wood that was 2,000 years old! It was worth going into that tight space.
What were you looking for during that season of excavation?
Even though there were some writings that suggested that tsunamis had happened in the past, we didn’t have any proof of tsunamis on land. One of the problems was that in an archaeological site on a coastline there tends to be a lot of sand, pottery, shell, and gravel. Guess what is usually in a tsunami deposit? The same things! This made it hard to realize that some of those layers in the site were actually from a tsunami event and not just material from building the site.
To confirm their suspicions, the team looked for evidence of tsunamis below the surface.
Goodman collects a sediment sample in a small bag.
Goodman shows students what the inside of a core sample looks like.
We collected evidence using a few different techniques. The first evidence was collected during underwater archaeological excavations. These excavations are done using something called a water dredge, which is sort of like an underwater vacuum cleaner.
The evidence that we found in those excavations, and later in core samples, was layers of materials that came from the deep sea mixed with materials from the shallow sea and beach, and material that came from the land. The mixture included pottery, shells, pebbles, microscopic organisms, patches of mud, and sometimes even large pieces of carved marble. The only thing that could cause this would be very strong waves.
The team then linked this mix of material with what they knew about the past.
Once we recognized this evidence, we looked at the written evidence and discovered that the age of these deposits was the same as the age of the events we read about.
The discovery was really important for proving that the written records were not describing regular storms or other events, but actual tsunamis. It also told us that people living there today might need to prepare for a tsunami happening in the future.
The team wanted to get a fuller picture of what was underwater. But they didn’t have the right tools. They needed to invent something to solve their problem.
We knew that, if what we found was evidence of an ancient tsunami, the debris field should be very large. To find out, we needed to take core samples using long pipes that we insert into the seafloor. The problem was that this is not so easy to do in sandy seafloors. You need to really hammer the pipe in a long time, and then you must remove it somehow.
Everyone worked together to think about how we might connect an automatic hammer to the top of the pipe to hammer it in, then attach ropes and floats to pull it out. It took a lot of sketching, thinking, and trial and error until we got it right. The first season, we collected two cores in 12 days. Now, we can collect three cores in a single day!
Problem-solving is really important in exploration. Sometimes you have to build the tool that you need. This is one of the parts of exploration that I love the most.
Goodman holds steady a pipe being used to take a core sample of the seabed.
