1A2 Geography 14 th April, 2015 Objectives: 1. To review the causes of carbonation and the formation of karst landscapes. 2. To explain the formation of two surface features that can be found in a karst region – Limestone pavement & swallow hole.

Homework: For Monday’s class, you must complete Question 3, page 103 of your textbook. “Explain, with the aid of a diagram, how any two karst surface landforms are formed.”

This morning… We learned about chemical weathering and the formation of karst landscapes. With your partner, explain carbonation and the formation of karst landscapes using the following words: Rain waterCarbonic acid LimestoneCarbon dioxide DissolvesCalcium carbonate

Surface features: Limestone Pavement When rain water falls on to exposed limestone, it passes through joints in the rock. Carbonation leads to the weathering of the surface of the limestone and the joints within the rock. As a result, the joints become wider.

Surface features: Limestone Pavement The widening of the joints leads to the creation of grooves or gaps in the limestone called grikes. The blocks that are left in between these grikes are called clints. limestone pavement The combination of these features leads to the creation of a limestone pavement. Grikes Clints

Surface features: Swallow Hole Another landform created by chemical weathering in a karst region is a swallow hole. Swallow holes are formed by rivers dissolving limestone rock. A river may disappear underground once it reaches a limestone surface.

Surface features: Swallow Hole A river widens the joints and bedding planes of limestone rock through carbonation. It will then disappear underground through a swallow hole. The size of swallow holes is generally determined by the size of the river that created them. For example, Pollnagollum in the Burren is over 6m wide and 16m deep.