How did this land get here? EarthCache

Did you notice that you are standing in the midst of San Diego Bay?

Less than 100 years ago (1934 specifically) this was just a thin sandbank only visible at Low Tide. See the picture above (PHOTO COURTESY OF JACK DAVIS COLLECTION) to see how it used to look. Now it has become “something from nothing.”

But what is this something that you are now standing on? See the picture above (PHOTO COURTESY OF SHELTER ISLAND HOTEL GROUP) to see how it looks now. And what has happened to the nothing that was here before? How has the Earth changed in this area?

The land you are now standing on is referred to as Shelter Island. You can now see it, in addition to driving, walking, and playing, all day long thanks to depositing the results of dredging of San Diego Bay. The first dredging efforts were for yachting purposes. During World War II, the US Navy had dredging requirements that helped raise Shelter Island permanently above the tides.

Dredging is the removal of sediments and debris from the bottom of lakes, rivers, harbors, and other water bodies. It is a routine necessity in waterways around the world because sedimentation—the natural process of sand and silt washing downstream—gradually fills channels and harbors.

Dredging often is focused on maintaining or increasing the depth of navigation channels, anchorages, or berthing areas to ensure the safe passage of boats and ships. Vessels require a certain amount of water in order to float and not touch bottom. This water depth continues to increase over time as larger and larger ships are deployed. Since massive ships carry the bulk of the goods imported into the country, dredging plays a vital role in the nation's economy.

To get credit for this EarthCache, while you are enjoying your time on Shelter Island, please answer the following questions in a message to the Cache Owner.

1. At the posted coordinates for this EarthCache, please observe the rocks along the water line.
   1. Note the time of day you are visiting the site, and if it appears to be low tide or high tide?
   2. Are these rocks what you would typically envision finding along the water? On something that was originally referred to as a sandbank?
2. At the posted coordinates for this EarthCache, look out onto the water and observe the water.
   1. Describe how the bay looks today? Is the water calm or choppy? 
   2. Do you see an indication of a current? Which direction is it flowing?
3. Now make your way to the additional waypoint, identified as “What Do you see here?”. Look out into the basin and observe the water from this position.
   1. Describe how the basin looks today? Is the water calm or choppy?
   2. Do you see an indication of a current? Which direction is it flowing?
4. Using your observations from questions 2 and 3, answer the following questions:
   1. Does the water look the same in both the bay (question 2) and the basin (question 3)?
   2. What similarities do you observe?
   3. What differences do you observe?
   4. Do you think these similarities and differences observation would be same 100 years ago when only a sandbar was here (that disappeared at high tide)?
   5. Do you think dredging resulted in any of the changes you observed?
5. (OPTIONAL): Take a picture of yourself (and others) enjoying yourselves at the original coordinates and/or additional waypoint and post it with your Found It log? Double Optional points for positing pictures from both locations!

References:

• https://en.wikipedia.org/wiki/Shelter_Island%2C_San_Diego
• https://sandiegohistory.org/journal/1974/october/yachting/
• http://sdnews.com/view/full_story/27568369/article-Bate-s-folly---and-the-development-of-Shelter-Island-?instance=most_popular1
• https://en.wikipedia.org/wiki/Dredging
• https://oceanservice.noaa.gov/facts/dredging.html