Ripple Marks at Sand Dollar Beach EarthCache

Ripple Marks at Sand Dollar Beach

MUST BE DONE AT HALF TO LOW TIDE

Sand Dollar Beach is a hidden gem at high tide until the ocean reveals it for you to explore at low tide. This unique beach is considered a hot spot for sand dollars, sea shells, and other treasures the tide has left behind. When the tide is out you are able to see the sand bar for a kilometer. You have to be careful not to get caught on the other side of the sand bar when the tide changes. It is a nice swim too as the water warms up as it comes in over the warm sand. Parking is available but limited.

Sandbar - A sandbar is formed by deposition of sediment via longshore drift. It can also be called an Offshore Bar, submerged or partly exposed ridge of sand or coarse sediment that is built by waves offshore from a beach. The swirling turbulence of waves breaking off a beach excavates a trough in the sandy bottom.

Tides and tidal currents - Tides are produced by the gravitational pull of the Moon and Sun acting on a rotating Earth. This pull produces a very slight bulge in the ocean, which we know as tide. The tides and the currents they generate are responsible for about 50% of the marine energy delivered to the coast. The major impact of tides is to shift the shoreline between high and low tide, and to generate tidal currents either parallel to the coast, or at tidal inlets and estuaries, currents flowing into the inlets and perpendicular to the coast.

Wind and currents - Winds blowing over the oceans are responsible for generating ocean waves. Nearer the coast they can generate local seas. They can move the ocean surface and generate locally wind driven currents which in places can result in upwelling and downwelling. Finally, when blowing over the beach, they can transport sand inland to build coastal sand dunes.

Ripples

When the tide is out you can see ripple marks etched in the sand. In geology, ripple marks are sedimentary structures (i.e., bedforms of the lower flow regime) and indicate agitation by water (current or waves) or wind.

Ripple marks indicate that sediments were deposited in an environment characterized by moving water or air. Ripple marks range from a few millimeters to centimeters in size. There are 2 types of ripple marks, asymmetric ripples and symmetric ripples. Symmetric ripple marks are the result of wave activity, in which sand grains are regularly swooshed back and forth creating ripples that have two more or less symmetric slopes. Asymmetric ripples are generated by directional currents, for example in rivers or on tidal flat.

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MUST BE DONE AT LOW TIDE

Questions:

1. What direction do the ripples run (NEWS)?

2. What kind of ripples are they and why, see above chart (waver or current)?

3. How big an area is covered with ripples (acres)?

4.Post a picture in your log with a personal item or hand in picture to prove you were there.

[REQUIRED] In accordance with the updated guidelines from Geocaching Headquarters published in June 2019, photos are now an acceptable logging requirement and WILL BE REQUIRED TO LOG THIS CACHE. Please provide a photo of yourself or a personal item in the picture to prove you visited the site.