New Geography in Action Junior Cycle Geography Sand spits
A sand spit is a long ridge of sand or shingle that stretches across a bay and is connected to one side of the bay.
Formation: • Longshore drift loses its energy and deposits the material it is carrying when it is interrupted by a sheltered bay.
• The material builds up over time and gradually extends across the bay. A sand spit is formed.
• As the sand spit increases in size, vegetation grows on it and a beach can form on the side facing out to sea.
• The end of the spit is often curved due to the current.
Example of a sand spit: Rossbeigh Strand near Glenbeigh, Co. Kerry.
Lagoons
A lagoon is an area of water that has been cut off from the sea by a sandbar. Formation:
A sandbar forms when a sand spit continues to grow across a bay until it connects with the other side. The bay is then cut off from the sea, and a lake, called a lagoon, is formed.
Example of a lagoon: Lady’s Island Lake in Co. Wexford.
Tombolos
A tombolo is a ridge of sand that connects the mainland to an island. Formation:
A tombolo is formed when longshore drift creates a sand spit in the sheltered waters between the mainland and an island.
Example of a tombolo: Howth in Co. Dublin was once an island but is now connected to the mainland by a tombolo. Nearby Sutton is built on this tombolo.
: Figure 10.18 A tombolo connecting an island to the mainland in Scotland
ACT VITY
Can you apply the D-E-P-E-D formula to explain one feature of coastal deposition to your classmates? Use the outline on page 46 of your Activity Book to help you.
166 Tombolo Lagoon Sandbar Longshore drift : Figure 10.17 Landforms of coastal deposition Sand spit : Figure 10.16 A sand spit at Rossbeigh Strand, Co. Kerry
