PLEASE READ DESCRIPTION BEFORE COMPLETEING LOGGING REQUIREMENTS
Introduction
Welcome to Shark Tooth Island. This island is popular among residents, and visitors alike. The island resides in the Cape Fear river. You can access the island from nearby River Road Park. The island is relatively well known for its abundance of shark teeth. From Megalodon to Mako, there is nearly every type of shark here. In this Earth Cache lesson we will be going over the geology, and the shark teeth, of shark tooth island. We will learn how it was formed too.
How was Shark Tooth Island formed?
As you may know; the port of Wilmington is one of the biggest in the region. The Cape Fear river is known for having lots of cargo ships travel to and from the port. The port itself is about 5.25 miles north of the posted coordinates on Shark Tooth island. Container ships are big ships, therefore they need deep water. And in turn the water to be dredged. The Cape Fear is repeatedly dredged for said ships. They have to put the sediment somewhere though. Back in the late 1800's large maritime vessels had to navigate the water safely. That is why they dredged the river. All that sediment was dumped in big 'piles' which create the islands you see in the cape fear today. Shark tooth island is one of these. From one tip the other shark tooth island is about 0.1 miles wide. Think about the thousands of tons of sand dredged and put there to form that island. Not to mention places like campbell island that are 1.4 miles from point A to point B, with likely millions of tons of sediment there. Since then nature has done a great job of refurnishing the island with plenty of plants and trees.
Archeoligy of Shark Tooth Island
hence the name "Shark Tooth Island" you could probably make the inference that there is an archaeological background behind it. 5 million years ago the coastline was 100 miles inland near Fayettville. Earth goes on roughly 100,000 year cycles of natural warm, and cold periods. In these warm periods the climate changes and the ice bergs melt. Therefore the ocean level rises. During the cold periods ice bergs form letting the ocean recede. This is called natural climate change, it happens as the earth gradually tilts on it axis. Currently our last ice age was around it's peak 20,000 years ago. Now we are moving into a more warm phase. Because of the ocean coming and receding every 100,000 years, a lot of bio-matter and fossils are left behind. That is why if you search the sand in pratically anywhere in southeastern nc you will find little shell rock fossils. Since shark skeletons are made out of cartilidge they don't last very long. Cartilidge is the same stuff our noses and ear lobes are made of. Like humans they will only leave behind their teeth, like we only leave behind our bones. That is why we only find shark teeth, and not shark collar bones. In terms of what you can find on shark tooth island; there are a variety of teeth. From rare instances of megalodon finds, and other extinct sharks, too more common instances of things like makos, white tips, and sand tigers. Apart from archeoligy there are things to find such as native american, and civil war artifacts. You may also enjoy the island if you are a marine bioligists do to its plethora of species. Most of these teeth are from 30-40 million years ago.
Fossilization of Shark Teeth
Since Shark Tooth island is mainly known for its archaeology, this section will go deeper into the topic. We will talk about how fossilization works. We all know that sharks shed 1000's of teeth throughout there lifetime, right? But what you may not know is that not all of these are fossilized. In order for these teeth to be fossilized they need to rapidly sink to the sea floor and be covered by sediment. (In this case the 'sea floor' is the Cape Fear river basin). Being covered in sediment helps for many reasons. Including; weathering, and abrasion that could occur if the teeth were exposed to open water. Secondly; burial separates the teeth from lots of bacteria, and oxygen which help in the decaying process. Shark teeth are fossilized over a course of a few thousand years through a process called permineralization. This occurs as water seeps through the sediments and over the teeth, depositing minerals into open pore spaces in the teeth. The most common minerals to be deposited are silica, and calcite. These minerals may also effect the color of the tooth.
How to log this cache
Use the image below with types of Shark Teeth to help with the logging requirements. Answer all questions and message my Geocaching profile with your answers.
Questions
1. I would like to build up a data base of the number of shark teeth found on average in each time of the year. So please set a timer for 45 minutes and start searching for shark teeth. Please tell me how long it took you to find said shark teeth and what day you found them on. If you can't find any teeth then tell me that.
2. Based on if you found any shark teeth use the image above and tell me which kinds you found. Not every kind of tooth may be on the chart. If you found a tooth that doesn't look like anything on the chart than tell me that to. Commonly shark teeth will be split in half or in pieces. If so than send me a picture of that.
Feel free to post pictures of the island or shark teeth in your log. I will add them to the cache page.
Happy Hunting! :)
Pictures
Zadventurer's Shark Teeth