Sharks have been on the planet for over 200 million years, and frequently shed their teeth. Most sharks can shed thousands of teeth every year. As these teeth drop onto the ocean floor, they are covered by sand and other sediments. Over the course of around 10,000 years, the teeth fossilize.
An old tooth covered in sediment does not mean that it becomes a fossil. Specific conditions are needed to prevent the tooth from decaying over time. Scavenging animals and insects, bacteria, weather, and erosion all can prevent fossilization. Most fossilization occurs in sedimentary rock formations, meaning that the surrounding environment is a combination of sand, rock, dirt, and other sediment materials.
Fossilization means that the bone of an organism, protected from decay by sediment, must become rock. Like our teeth, shark teeth contain calcium and oxygen. To become rock, the sediment-covered teeth are covered by even more sediments, creating intense pressure. As pressure increases, the minerals from the sediment try to fill in any empty space. This forces the oxygen in the teeth to absorb the surrounding minerals, creating a fossilized tooth. While newly shed teeth are white, fossilized teeth can be black, brown, gray, creme, or red. The color of the fossil depends on what minerals surround it during the fossilization process.
Myrtle Beach is dredged every year to rebuild the beach. Dredging digs into sand well below the top of the ocean floor, uncovering sediment formations that contain fossils. As the tide comes in and out, called wash-in, shark teeth are uncovered and washed onto the shore. The geological formations in Myrtle Beach produce fossils from between the Cretaceous period (about 145 to 72.1 million years ago) and the Pliocene Ephoch (about 5.3 to 3.6 million years ago), meaning that the fossils found on the shore from dredging and wash-in were formed long before humans evolved.
Most of the shark teeth found on Myrtle Beach are very tiny. Lesser known beaches and rivers can contain larger shark teeth, but there are still many teeth along the public beaches thanks to dredging. Low tide is the best time to search for shark teeth because shells, rocks, fossils, and other sediments are not washed away by the tide. You can find collections of these sediments along the shoreline. Fossils are more dense than shells, so they are often below the first layer of sediment.
Please email the answers when logging this cache as found. Logs without answers will be deleted.
1. Is it high tide or low tide?
2. As you walk along the beach, can you see collections of sediment?
3. As you look at the shells in sediment collections, which type of shell looks most like a shark tooth?
4. Did you find a shark tooth today?
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