This earthcache is a chance to visit one of the three major shingle structures in the United Kingdom. Chesil Beach is 18 miles long and this cache is located at the south end. It is off the A354 which connects the Isle of Portland to the mainland.

This is accessible with plenty of parking. Geocachers in wheelchairs will be able to access the information needed to answer the questions however the beach itself is not accessible due to the pebbles and gradient of the beach.

Information

Chesil beach is made up of over 180 billion pebbles. They are naturally sorted with the smallest pebbles at the north west end and the largest pebbles at the south east end. Although Chesil beach looks like a tombolo, it is actually a barrier beach which has moved towards the land.

What is a Tombolo

A Tombolo is a coastal landform that connects an island to the mainland. They are formed because islands bend the waves disrupting the normal process of transportation (long shore drift) that happens along the coastline.

What is a Barrier Beach

A Barrier Beach is a beach that is formed just off the shore which forms parallel to the coast. It forms because the waves loose energy as the water depth decreases. Because the waves loose energy they drop (deposit) some of the sand/pebbles (load) that they are carrying before they reach the shore. Over time this builds up and forms a barrier beach, sometimes referred to as a sand or shingle bar. Between the barrier beach and the shoreline is water referred to as a lagoon.

The Fleet and Chesil Beach

The fleet is an eight mile long salt water lagoon that is protected by the beach. Today this is a haven for a variety of rare birds. During the second world war this was used as a testing site for the bouncing bombs used by the 'dam busters.

Chesil beach and the fleet are part of the Jurassic Coast UNESCO World Heritage site. For more information about the Jurassic Coast World Heritage site visit the official website.

There is a visitors centre near this cache location along with public toilets and a kiosk selling refreshments. Please be aware that this is a site of special scientific interest. The pebbles are great to hold and touch but please don't take them with you; this is illegal and can result in a fine of up to £2,000.

Tasks.

To log this earthcache please send me the answers to the following questions. The answers can be found on the interpretation boards around the area. They are mainly next to the fleet near the visitors centre.

1. What is the principle rock type of Chesil Beach?
2. What is the average diameter of the pebbles at this point on the beach? (guess, in centimetres)
3. What process made the pebbles so smooth and round?

Optional Task: Take a picture of your GPS unit lying on the shingle.