Sea Floor

What are conditions like on the seafloor? It is in absolute darkness, with temperatures near freezing. The water is 3.5 kilometers high and exerts a pressure hundreds of times greater than atmospheric pressure on Earth.
What is the main type of igneous rock found on the seafloor? Basaltic rock is heavy and sinks forming the world’s deep ocean basins.
Describe the topography of the seafloor: shelf, slope, canyons, rise, and abyss. Continental shelf, the most shallow and accessible region, they cover 1/6 of Earth’s surface. Continental slope from the edge of the continental shelf to the deep ocean. Continental rise is a huge long shallow slope where debris coming off the continent is deposited, and is a gradual slope. Submarine canyons are deep v-shaped valleys that furrow continental shelves and slopes. The abyssal plain is beyond the continental rise and is the flattest region on Earth and is formed as layer upon layer of sediment settles on the ocean floor
What are terrigenous and pelagic sediments? Pelagic sediment consists of organic and inorganic matter and is not restricted to the abyssal plain, but occurs throughout the oceans. The entire surface of the sea floor is volcanic in origin.
What do oceanic ridge systems represent? The ridges are connected in a single system snaking across the undersea landscape from one ocean to another.
What is found at the crest of the oceanic ridges? A cliff rimmed valley extending along much of its length. The walls and the floor of this valley are split by numerous fissures.
Discuss the age of the ocean floor as it relates to the oceanic ridge systems. There was a great disparity between the age of continental crust and oceanic crust. The rock under the continents is 4 billion years old and the oldest rock found beneath the ocean was 200 million years old. Fossils of marine organisms were found and were 2.8-3.5 billion years old. The oceans did exist throughout Earth’s history but what has happened to the crust?
What is seafloor spreading, and what does it do to the ocean floor? The sea bed becomes steadily older with increasing distance from the mid-ocean ridges. The sea floor originates and grows outward from the ridges. When this process is repeated continuously over millions of years it forms new sea floor
What is subduction, and what does it do to the ocean floor? Sinking of the oceanic crust and explains the absence of very ancient sea floor, it disappears back into the earth.
Discuss methods used by marine geologists to study the seafloor. The primary tool is a research vessel. The A-frame which is a hydraulically movable rack used to lift and deploy the instruments. A camel grab takes a sample of sediment from the ocean floor quickly and upper few centimeters. A box corer takes an entire column of sediment which later can be split open and the individual layers can be analyzed.
What types of metallic resources can be found on the seafloor? Oil and gas geologic resources. Copper, zinc, iron, gold and other metals at mid ocean ridges. Nodules of manganese ore are scattered by the millions.
What conditions limit exploration and development of resources from the seafloor? There are serious environmental concerns.
Describe the ecological environment found at hydrothermal vent sites. They range from just a little bit warm to outrageously hot 350 degrees centigrade. Normally water would boil at 100 degrees centigrade but because of the high pressure it doesn’t boil. When it is cooler, there are a lot of strange animals living there, on the chemical energy that’s in the water of the vents. A different ecological situation than we are used to. The conditions on the sea floor are absolute darkness and temperatures near freezing. The water is 3.5 kilometers high and exerts a pressure hundreds of times greater than the atmospheric pressure on Earth. Basaltic rock is the main type of igneous rock found on the sea floor. The continental shelf is the shallowest region and covers 1/6 of the Earth’s s surface. The continental slope is from the edge of the shelf to the deep ocean. The rise is a huge shallow slope where debris from the continent is deposited. The abyssal plain is beyond the continental rise and is the flattest region on Earth. Pelagic sediment is made of organic and inorganic matter and occurs throughout the oceans. Oceanic ridge systems represent the fact that ridges are connected in a single system across the sea from one ocean to another. Sea floor spreading is when the sea floor grows outward from the ridges, and when this is repeated continuously over millions of years it forms new sea floor. Sinking of the oceanic crust is known as subduction and it causes the ocean floor to disappear back into the Earth. Marine geologists use various methods to study the sea floor, and the primary tool is a research vessel. There are metallic resources that can be found on the sea floor such as copper, zinc, iron and other metals. There are serious environmental concerns that limit exploration and development of resources from the seafloor. The ecological environment found at hydrothermal vent sites range from a slightly warm to 350 degrees Celsius. Water would normally boil at 100 degrees Celsius, but the high pressure prevents this from happening. When the water in the vent sites is cooler, there are a variety of different animals thriving in the environment.