Continental Shelves
The ocean floor slopes gently downward, away from the continents. This continental shelf abounds in sea life. some parts of the shelf are as narrow as a kilometer, while other parts, like the grand banks off Newfoundland and Labrador, extend several hundred kilometers. the continental shelf is a part of the continental crust and is an extension of the continent, even though it is under the ocean.
The edge of the continental is a more steeply sloped region called the continental slope. The continental rise is a region of gently increasing slope where the ocean floor meets the continental slope. the continental rise is the area of the crust surface where the oceanic plate meets the continental plate.
The ocean floor is beyond the continental slope and rise. Much of the ocean floor consists of large flat areas know as the abyssal planes. Sediment brought from the land by rivers and streams settles on the bottom of ocean and covers the original landscape. The sediment fills up holes and basins and levels off the floor over time.
The edge of the continental is a more steeply sloped region called the continental slope. The continental rise is a region of gently increasing slope where the ocean floor meets the continental slope. the continental rise is the area of the crust surface where the oceanic plate meets the continental plate.
The ocean floor is beyond the continental slope and rise. Much of the ocean floor consists of large flat areas know as the abyssal planes. Sediment brought from the land by rivers and streams settles on the bottom of ocean and covers the original landscape. The sediment fills up holes and basins and levels off the floor over time.
Underwater Mountains
You might be surprised to know that the longest mountain range is in the world lives underwater! The Mid-ocean ridge extends 60,000 km through all four oceans. Different sections of the Mid-ocean ridge have more specific names depending on their locations, such as the Mid-Atlantic ridge.
A volcano is a mountain that is formed when hot lava erupts through the earths crust, cools, and solidifies into rock as it flows down the surface of the volcanic cone. There are a number of locations around the world where volcanoes originated on the ocean floor. An under water volcano is called a sea mount. Over time , as the lava builds up, a volcanic island is formed. Some of the best known volcanic islands in the world are the Hawaiian islands.
A guyot was once a volcanic island. Over time, with the continuous pounding of the sea and erosion on the surface, the top of the volcanic island eroded enough that the ocean covered it again.
A volcano is a mountain that is formed when hot lava erupts through the earths crust, cools, and solidifies into rock as it flows down the surface of the volcanic cone. There are a number of locations around the world where volcanoes originated on the ocean floor. An under water volcano is called a sea mount. Over time , as the lava builds up, a volcanic island is formed. Some of the best known volcanic islands in the world are the Hawaiian islands.
A guyot was once a volcanic island. Over time, with the continuous pounding of the sea and erosion on the surface, the top of the volcanic island eroded enough that the ocean covered it again.
Canyons and Trenches
Canyons are deep steep sided valleys. Most canyons are formed by rivers that cut their way through the surrounding rocks. As these rivers run into the ocean they may continue to erode the sea bed carving valleys and canyons into the continental shelf. Geologists think that many sea canyons were caused by rivers flowing over the coast before the sea level rose.
Trenches which run parallel to the coast are formed where two oceanic tectonic plates converge. Trenches may be as much as 200 km wide and 24 km long.
Trenches which run parallel to the coast are formed where two oceanic tectonic plates converge. Trenches may be as much as 200 km wide and 24 km long.
Watersheds and the Continental Divide
Imagine a large flat area of land. The land is covered by a calm shallow sea. Over millions of years the land buckles and heaves as the tectonic plates of earth's crust shifts. Large areas rise up, forming mountains. Pulled by gravity, water moves with the changing land. As the ground rises the water is divided some flows down one side of the upthrust land and some flows down the other. The flowing water carves valleys and canyons in the new landscape forming pathways for future water to travel.
A water shed is an area surrounded by high elevation land, in which all water runs to a common destination. A large river such as the Fraser River is fed by rivers from several water sheds on it's way to the Pacific Ocean. The large watershed that feeds the Fraser River is known as the Fraser Basin. There are 13 main watersheds within the Fraser Basin. Each watershed contains smaller watersheds each of which contain even smaller watersheds.
The Continental Divide follows the crest of the Rocky Mountains and separates water flowing to the West into the Pacific Ocean from water flowing North and East. The Columbia Ice Field, composed of more than 30 glaciers lies at the heart of the Continental Divide. The meltwater from this ice field drains into three oceans: Pacific, Atlantic, and Arctic.
There are two extensions of the Continental Divide running North East and East across the continent. These extensions form ridges of higher land that direct the flow of water to either the Arctic Ocean, Hudson's Bay, or the Atlantic Ocean.
A water shed is an area surrounded by high elevation land, in which all water runs to a common destination. A large river such as the Fraser River is fed by rivers from several water sheds on it's way to the Pacific Ocean. The large watershed that feeds the Fraser River is known as the Fraser Basin. There are 13 main watersheds within the Fraser Basin. Each watershed contains smaller watersheds each of which contain even smaller watersheds.
The Continental Divide follows the crest of the Rocky Mountains and separates water flowing to the West into the Pacific Ocean from water flowing North and East. The Columbia Ice Field, composed of more than 30 glaciers lies at the heart of the Continental Divide. The meltwater from this ice field drains into three oceans: Pacific, Atlantic, and Arctic.
There are two extensions of the Continental Divide running North East and East across the continent. These extensions form ridges of higher land that direct the flow of water to either the Arctic Ocean, Hudson's Bay, or the Atlantic Ocean.