Explore the Mysteries of the Ocean

Introduction to Oceanography

• The Earth’s surface is 71% water and 29% land, with 140 million miles of water and 58 million miles of land.
• The northern hemisphere has more land than the southern hemisphere, with a 39% land and 61% water distribution compared to 19% land and 81% water.
• An echo sounder is an instrument used to determine the depth of the ocean, while a multibeam has not fully mapped out the ocean due to its vastness and cost.
• The continental margin is the portion of the seafloor adjacent to the continental shelf, slope, and rise, with the continental shelf being a gently sloping submerged portion of the continental margin, the continental slope being a steep gradient that leads to the ocean floor, and the continental rise being a gently rising base.
• An active margin is a narrow, deformed sediment, subducted continental margin, while a passive margin has a continental shelf, slope, and rise.
• Submarine canyons form through turbidity currents, while atolls are remains of a volcanic peak covered with coral.
• Seamounts are isolated volcanic peaks that rise at least 3,000 ft above the ocean floor, while guyots are submerged flat-topped seamounts, and abyssal plains are deep, flat sea floors.
• Terrigenous sediments are derived from terrestrial weathering and erosion, biogenous sediments consist of material of marine organic origin, and hydrogenous sediments crystallize from seawater.
• Minerals obtained from the sea include salt, halite, sodium chloride, and gypsum, with seawater evaporating as the source.
• The ocean’s salinity is 3.5% or 35 parts per thousand, affected by rain, snowfall, river discharge, evaporation, formation of sea ice, volcanic eruptions, and river runoff.
• Water density affects positioning in the ocean, with dense water sinking and less dense water rising due to convection.
• The thermocline is a layer of water in which rapid temperature changes happen vertically, while the pycnocline is a layer of water in which there is a rapid change with depth.