"What is that?" Wednesdays

Today's features are beautiful Neap-Spring Tidal Bundles from the Eocene Delmar Formation in the outcrops along Torrey Pines Beach in San Diego California.

High tide and low tide typically occur twice a day, and when we see the biggest difference between the high and low tide we call this the spring tide, but when we see the smallest difference we call this the neap tide.

Spring tides occur when the sun, moon, and earth are in a line resulting in a large difference between high and low water. Neap tides occur when the moon makes a right angle between the sun and earth, allowing for a smaller difference between high and low water.

During the neap tide, when the tidal current strength is weakest, smaller quantities of finer grains are deposited, resulting in the thin stratigraphic packages as seen in the outcrop. As the tidal variation grows larger, towards the spring tide, larger quantities of coarser material will be deposited which results in the increasing bed thicknesses we saw on the outcrop.

This may have been one of the most beautiful neap-spring tidal bundles I have ever seen, they were cool enough to impress a structural geologists!

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