1 For an observer on the ground with eye level at h = 5 ft 7 in (1.70 m), the horizon is at a distance of 2.9 miles (4.7 km). 2  For an observer standing on a hill or tower 100 feet (30 m) in height, the horizon is at a distance of 12.2 miles (19.6 km).
The mantle is a layer of the Earth between the crust and the core. The upper mantle starts below the crust and goes down to a depth of around 200 miles to the boundary with the lower mantle. The temperature of the mantle ranges from 900 degrees Fahrenheit near the crust to as high as 7000 degrees near the core.he Upper Mantle: Temperature and Depth. The upper mantle begins just beneath the crust and ends at the lower mantle. The thickness of the upper mantle is between 200 and 250 miles.
The Upper Mantle: Temperature and Depth. The upper mantle begins just beneath the crust and ends at the lower mantle. The thickness of the upper mantle is between 200 and 250 miles.The entire mantle is about 1800 miles thick, which means the lower mantle makes up the bulk of this part of the Earth. The temperature of the mantle near the crust ranges from 900 to 1600 degrees Fahrenheit. It gets hotter at greater depths.The lower mantle near the core is as hot as 7000 degrees Fahrenheit. The upper mantle is not uniform throughout. The topmost, thin layer of it is very similar to the Earth's crust.he Upper Mantle: Temperature and Depth. The upper mantle begins just beneath the crust and ends at the lower mantle. The thickness of the upper mantle is between 200 and 250 miles.