A tombolo is a geological land formation that is formed due to the movement of sediment resulting from longshore drift, slowly building up a connection between a body of land and an island. Longshore drift is the movement of sediment due to the angled direction of incoming waves caused by prevailing wind direction.
The tombolo at this location connects the mainland north of Sydney to Barrenjoey Headland, which would once have stood as an island separate from the mainland. The tombolo has created, or extended, Palm Beach on its eastern, seaward, side and enjoys a starring role as the setting for "Summer Bay" in the popular Australian soap opera "Home and Away".
This Earthcache
To complete this earthcache, you're going to do some exploring along the tombolo, and then you're going to answer some questions about it. You MUST physically visit the location to complete this earthcache. If you can park somewhere around the published coordinates - this would be a good place to start.
In order to log this earthcache as found, you must send your answers for the questions below in an email to the cache owner via our geocaching profile. Any photos should be uploaded with your online log.
1. Take a walk around the tombolo and find out the length of the tombolo (in metres), from the last rock outcrop on the mainland (southern end) to the nearest rock outcrop on the "island" (northern end).
2. What is the elevation above sea level of the highest point on the tombolo at one quarter, half way, and three quarters of the way along the tombolo from the mainland? Also, at each of these points, was the highest point in the centre or closer to the eastern or western side?
3. Imagine if you could cut a slice across the tombolo, east/west, describe the typical profile and explain if this gives you any clues as to how the longshore drift process has created the tombolo. Also, does this indicate the tombolo is still growing?
4. Finally, take a walk up to the top of Barrenjoey Headland and tell us the elevation at the top. Optionally, but recommended, please take a photo looking back over the tombolo towards Sydney, including your GPS in the photo if possible.
You can log this cache straight away after you have emailed your answer to the cache owner, no need to wait for confirmation. Please include the name of this earthcache in the email - you'd be surprised how many people forget. Also, when contacting us with answers, if you want a reply, please include your email address. Any problems with your answers we'll be in touch.
Happy Earthcaching!
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bella at waggy |