Welcome to Por do Sol Cliffs EarthCache
TASKS
- Looking at the cliffs in front of you, please describe what you see [colour; layers, etc] and how the sea might have interacted with the cliffs over the years.
- Estimate the height of the cliffs. [nearest metre in your estimate.]
- What structure do you see when looking NE from where you are standing.
- OPTIONAL - go to the bottom of the road and take a photo looking up the cliffs.
Send answers to cincolcc@gmail.com
DESCRIPTION
In geography and geology, a cliff is a vertical, or nearly vertical, rock exposure. Cliffs are formed as erosion landforms by the processes of weathering and erosion. Cliffs are common on coasts, in mountainous areas, escarpments and along rivers. Cliffs are usually formed by rock that is resistant to weathering and erosion. Sedimentary rocks most likely to form cliffs include sandstone, limestone, chalk, and dolomite. Igneous rocks such as granite and basalt also often form cliffs.
Source : http://www.discoveringfossils.co.uk/coastlines.htm
An escarpment (or scarp) is a type of cliff, formed by the movement of a geologic fault or landslide, or by differential erosion of rock layers of differing hardness.
Most cliffs have some form of scree slope at their base. In arid areas or under high cliffs, they are generally exposed jumbles of fallen rock. In areas of higher moisture, a soil slope may obscure the talus. Many cliffs also feature tributary waterfalls or rock shelters. Sometimes a cliff peters out at the end of a ridge, with tea tables or other types of rock columns remaining. Coastal erosion may lead to the formation of sea cliffs along a receding coastline.
What Is a Cliff?
The word cliff is derived from an old English word “clif” which refers to a near vertical or extremely vertical rock exposed from the surface. The main processes through which cliffs are formed are erosion, weathering, and tectonic activity. Cliffs are a common feature on the coastal lines, mountainous regions, escarpments, and along the river banks. Scientists have established that as the cliff agents invade an area, some rocks known as the sedimentary rocks become resistant to weathering. They are, therefore, left protruding vertically leading to the formation of a cliff. An outstanding feature of a cliff is a scree slope found in the base. A cliff can be big enough to form a mountain and some of the largest cliffs are found underwater in the sea
How Are Cliffs Formed?
Cliff formation is catalyzed by various agents. The major sedimentary rocks that form a cliff are dolomite, sandstone, and limestone. Types of igneous rocks which form cliffs include granite and basalt. The major processes involved in the formation of a cliff are discussed below.
Source : http:// www.slideshare.net/sidraqasim99/formation-of-coastal-features-33829716
Water and Erosion
A point of weakness is created when waves from the sea hit the land leading to a cut known as a notch. The notch erodes further resulting into a cave. The cave develops hallows along the land leading to a mass of hard rock. With time, more erosion takes place making the overhanging hard part of the cave to collapse into the sea. The sea water washes away the fallen part leading to the formation of a cliff. Continuous erosion and weathering cause the cliff to enlarge and retreat more into the land. Continuous lapping of water against the adjacent rocks leads to the formation of a vertically cut feature. Over thousands of years, only the very hard rocks are left standing, either vertically or sloping. The process leads to the formation of both huge and small cliffs.