Crescent Beach Tombolo EarthCache

Crescent Beach Tombolo

Crescent Beach crescent-shaped beach, with white sand, not far from the community of LaHave and the towns of Bridgewater or Lunenburg. The sand beach is separated from the tidal flats and salt marsh of Dublin Bay by sand dunes which rise in height from 2m in the west to 6.8m near the east end. The marsh behind the beach is one of the most important salt marshes in the Maritimes along the Atlantic Flyway for migratory shore birds, who come to rest and feed on their way South each year.

The Crescent Beach sand bar connects some of the LaHave Islands to the mainland. Prior to the construction of the paved road behind the dunes running the length of the backshore, the beach was primarily used as a path to and from George Island which is part of the LaHave Islands.

Automobiles are permitted on the actual beach itself, something rare in Nova Scotia.You can drive the beach or the road to help answer the questions.

What is a Tombolo?

A Tombolo is a deposition landform in which an island is attached to the mainland by a narrow piece of land such as a spit or bar. Once attached, the island is then known as a tied island.

How Is A Tombolo Formed?

Longshore Drift

Longshore drift occurs as waves push sediment (which may consist of sand, silt, and clay) towards the coastline at an angle. Instead of landing on the beach, this sediment begins to build up between the beach and an island, creating the bar mentioned above and effectively “tying” the island to the mainland. This drift is often influenced by the wind direction. When created by longshore drift, these formation are sometimes not considered a true tombolo.

Wave Diffraction And Refraction

A true tombolo is formed by wave diffraction and refraction. Waves move toward the coastline and are slowed down as they enter the shallower water. They first reach the islands that are close to the shore. Because these waves are moving at a slower than normal pace, they move around the island instead of over it. As the water moves more slowly around the island, it picks up sediment along the way. When the waves meet on the other side of the island (the side facing the coast), the sediment is deposited. This sediment continues to build up until it creates the sandbar that connects the island to the beach.

Changing Tombolos

Because of the unique shape of tombolos, they tend to be more likely to change over time due to weathering and tides than the regular coastline. Sometimes, the island at the end of the bar, or spit, is large enough that it supports commercial or residential activity. In order to prevent changes to the tombolo, the bar is reinforced with cement roads or parking lots. This prevents wind and waves from washing away the finer sediment on top of the bar.

To log this Earthcache visit the viewing location.  Please answer the following questions and send in a timely manner to my geocaching profile or email. Answers not received will result in deleted logs.

1. How long is the tombolo? (you can drive it)

2. How wide is the tombolo?

3. What unique features run between the road and the beach?

4. What unique feature of the sand allows you to drive a car on it?

5. Post a picture proving 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.