Archive for the ‘Geology’ Category

What is geodesy?

This item was filled under Facts, Geology, geodesy
Geodesists assign coordinates to points all over the Earth. Using the Global Positioning System (GPS), geodesists can accurately define the coordinates of points on the surface of the Earth in a consistent manner. This set of accurately measured points is called the National Spatial Reference System (NSRS), which allows different kinds of maps to be consistent with one another.

Developers, local officials, city planners, and many others use the National Spatial Reference System to determine land boundaries for development or conservation efforts. Government agencies also rely on the NSRS to update maps of the U.S. shoreline.

Geodesy is also critical to the transportation industry. Surveyors use the National Spatial Reference System as one of their tools to develop nautical charts. Mariners use these nautical charts and GPS to accurately position their ships. This technology, accurate down to a centimeter scale, allows mariners and commercial vessels to assess where the bottoms of their ships are relative to the bottom of the ocean. With this information, a ship can hold extra cargo, sinking deeper into the water, and still safely navigate through a channel. The ability to move more cargo at a time is direct economic benefit to the shipping industries and ultimately to the consumer.

In addition, geodetic data, specifically datum information, and water level data are critical for agency officials to properly plan, design, and engineer coastal restoration projects. These data provide baseline information that assist in the construction of phases of marsh restoration projects, for example.

Geodesy is the science of measuring and monitoring the size and shape of the Earth, including its gravity field, and determining the location of points on the Earth’s surface.

For more information:
National Geodetic Survey
him him him himNational Spatial Reference System
Diving Deeper Podcast, Episode 9 (May 20, 2009) -- What is geodesy?
Geodesy Tutorial, NOS Education

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What do geodesists do?

This item was filled under Facts, Geology, geodesy
Geodesists assign coordinates to points all over the Earth. Using the Global Positioning System (GPS), geodesists can accurately define the coordinates of points on the surface of the Earth in a consistent manner. This set of accurately measured points is called the National Spatial Reference System (NSRS), which allows different kinds of maps to be consistent with one another.

Developers, local officials, city planners, and many others use the National Spatial Reference System to determine land boundaries for development or conservation efforts. Government agencies also rely on the NSRS to update maps of the U.S. shoreline.

Geodesy is also critical to the transportation industry. Surveyors use the National Spatial Reference System as one of their tools to develop nautical charts. Mariners use these nautical charts and GPS to accurately position their ships. This technology, accurate down to a centimeter scale, allows mariners and commercial vessels to assess where the bottoms of their ships are relative to the bottom of the ocean. With this information, a ship can hold extra cargo, sinking deeper into the water, and still safely navigate through a channel. The ability to move more cargo at a time is direct economic benefit to the shipping industries and ultimately to the consumer.

In addition, geodetic data, specifically datum information, and water level data are critical for agency officials to properly plan, design, and engineer coastal restoration projects. These data provide baseline information that assist in the construction of phases of marsh restoration projects, for example.

Geodesy is the science of measuring and monitoring the size and shape of the Earth, including its gravity field, and determining the location of points on the Earth’s surface.

For more information:
National Geodetic Survey
National Spatial Reference System
Diving Deeper Podcast, Episode 9 (May 20, 2009) -- What is geodesy?
Geodesy Tutorial, NOS Education

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What is a turbidity current?

This item was filled under Currents, Facts, Geology
Turbidity is a measure of the level of particles such as sediment, plankton, or organic by-products, in a body of water. As the turbidity of water increases, it becomes denser and less clear due to a higher concentration of these light-blocking particles.

Turbidity currents can be set into motion when mud and sand on the continental shelf are loosened by earthquakes, collapsing slopes, and other geological disturbances. The turbid water then rushes downward like an avalanche, picking up sediment and increasing in speed as it flows.

Turbidity currents can change the physical shape of the sea floor by eroding large areas and creating underwater canyons. These currents also deposit huge amounts of sediment wherever they flow, usually in a gradient or fan pattern, with the largest particles at the bottom and the smallest ones on top.

NOAA scientists use current meters attached with turbidity sensors to gather data near underwater volcanoes and other highly active geological sites. Also, satellite imagery is used to observe turbidity by measuring the amount of light that is reflected by a section of water.

For more information:
Ocean Geologic Features (pdf, 2Mb), NOAA Ocean Explorer
Ocean Turbidity, NOAA Coastal Services Center

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