Ria
Ria Landforms Have 2 Main Characteristics:
1. Partially submerged valley
2. Open to the sea or a large body of water
Example of a Ria Landform:
Narragansett Bay, Rhode Island, USA
What is a Ria Landform?
A ria is a valley that has been partially submerged by water near a coastline. There may also be other valleys feeding the main valley, forming a treelike pattern of branches. Often, one or more rivers feed the partially submerged valley. Rias that receive fresh water from rivers and streams are also estuaries when they occur on a seacoast, mixing freshwater and saltwater from incoming tides.
How are Rias Formed?
A substantial rise in sea level can form a ria. A fall of landmass on a coastline can also permit water to enter a valley and form a ria.
How Large is a Ria?
A ria can be from a few hundred feet wide to several miles in width and many miles long. A ria can be equal to the size of the valley that was submerged.
Where Can a Ria Be Found?
A ria may be found in an region of hills and valleys that descend toward the water as they near the coastline. Hilltops are the last to enter water, looking seaward.
Famous Rias
- Narragansett Bay, Rhode Island, USA
- Portsmouth Harbour, England
- Ria de Aveiro, Portugal
- Ria de Arousa, Galicia, Spain
Narragansett Bay on the Atlantic coast of New England is a ria formation of three submerged valleys, the longest which extends north to the cities of Providence and Pawtucket, Rhode Island. The bay is about 10 miles wide with islands that divide portions of the valleys below. The valleys are grabens that were formed by movement at fault zones in the area, causing parts of the land to drop. Glacier activity also played a major role in carving the land and altering sea levels. Portsmouth Harbour on the southern coast of England is a ria nearly 3 miles wide. It is a natural harbor with a narrow entrance, also protected by the Isle of Wight that lies off the coast. In addition to protection from heavy seas, it was strategically impossible for an enemy to successfully attack the harbor with guns protecting the entrance from both sides. The Ria de Aveiro is a 28 mile long estuary with many marshland areas. Much of the area has been allowed to remain in its natural state, providing a home for many bird species. The waters are also a popular tourist location and provide excellent fishing opportunities. Further north, in the Galacia region of Spain on the Atlantic coast, the Ría de Arousa is another estuary with two main rivers providing freshwater. The submergence of several interconnected valleys formed a body of water over 7 miles wide and 14 miles long. The Ría de Arousa is the largest of a series of rias that fill almost the entire west coast of Galicia.
Ria definition:
A partially submerged valley on a coastline, open to the sea or other large body of water