[Macfreak7]

Does anyone know how exactly this is done, and how and why "sea level" is taken into consideration? Also, what are the correct terms to describe the "tallest" or the "highest" peak?

Shouldn't the terms tallest / highest PEAK be synonymous since they're measured as the distance/height above sea level, even tho. peak 1 can be higher than peak 2 and still not be as tall as peak 2.

Any geologists want to share some information?

p.s. please save the links to wikipedia and such, i'd rather have a discussion here.

TIA

[Montezuma58]

They use GPS now. Also they can use general surveying techniques. I don't know all of the details of that though. If you have a sextant and know the distance to the peak it's height is easy to calculate.

I guess sea level is a convenient reference point even though that changes over time. I'm not sure what else they would use for reference. Any other point on the crust also won't be constant over a long period of time.

[tooki]

In Switzerland, which has a long history of astoundingly accurate cartography, they measured by literally scouring the whole country with a small contraption of meter-sticks and levels, creating an accurate three-dimensional image of the entire country by measuring rise over run manually. The Swiss coordinate system (which uses numbers in different ranges for each axis, so that number transposition cannot cause confusion) allowed centimeter-accurate geolocation about a century before GPS was invented. You can actually address mail by coordinates there if you like!

tooki

[f1000]

Originally Posted by Montezuma58

They use GPS now. Also they can use general surveying techniques. I don't know all of the details of that though. If you have a sextant and know the distance to the peak it's height is easy to calculate.

I thought geologists were using LIDAR now?

[SVass]

As one who dealt with some technical aspects of navigation, I can tell you that the "earth model" used has varied over time and both the shape of the earth and its "diameter" are subject to argument. I feel certain that there must be some silly international agreement on the definition of mean sea level. There is a different definition used for barometric pressure for airplane flights. sam

[Montezuma58]

Originally Posted by f1000

I thought geologists were using LIDAR now?

I don't doubt they do. GPS is just one way of getting data. I know they use GPS to monitor volcanoes since they can get info much faster than waiting for a plane or satellite to pass over the area.