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A map of measurements can be found here.

This appears to show that some of the highest values are found in the Andes and in parts of the Hymalayas.

I find this more than unexpected, so I suspect that this is the gravity referenced to some fixed height above sea-level rather than the surface gravity.

Jack Black's answer using a small sphere outside the surface seemed to me too extreme to establish the maximal case for real hills. It seems to me that an extreme model that looked at the maximum effect of a non-equilibrium covering be more definitive. So I have looked at the effect of a "mountain" that was so wide that it could be treated as a covering of uniform thickness across the entire globe.

Taking the field of the Earth at height h above the surface, and without covering we have

$$g_0 = 5510 \cdot G \cdot \frac{4 \pi}{3} \frac{R^3}{(R+h)^2} \frac{m}{s^2}$$

(5510 $\frac{kg}{m^3}$ being the mean density of the Earth, other symbols taking their usual meanings). The rate of change just above the surface is $$-2 \cdot 5510 \cdot G \cdot \frac{4 \pi}{3} \frac{m}{s^2m}$$ The rate of change of g at the surface of sphere with covering density $ \rho$ must then be $$3 \cdot \rho \cdot G \cdot \frac{4 \pi}{3} \frac{m}{s^2m}$$ It seems that the uniform surface covering must have a density more than 2/3 of the mean density of the Earth beneath it if gravity is to increase. This would be a rock with specific gravity of more than 3.67 if there is to be any chance that the gravity at the top of the "mountain" exceeds that at the bottom. The S.G. of the densest basalt is less than 3.1, and granite is even lighter (below 2.8).

This means that there is no realistic chance that a mountainous coating could result in an increase in gravity.

So the situation where hills/mountains might provide gravitational increases would be where we have steep inclines rising out of deep sea, as these provide an increase in density at levels below the sea-level surface. They would still not provide increases above standard gravity unless the total crust thickness in the region was less than average.

A map of measurements can be found here.

This appears to show that some of the highest values are found in the Andes and in parts of the Hymalayas.

I find this more than unexpected, so I suspect that this is the gravity referenced to some fixed height above sea-level rather than the surface gravity.

Jack Black's answer using a small sphere outside the surface seemed to me too extreme to establish the maximal case for real hills. It seems to me that an extreme model that looked at the maximum effect of a non-equilibrium covering be more definitive. So I have looked at the effect of a "mountain" that was so wide that it could be treated as a covering of uniform thickness across the entire globe.

Taking the field of the Earth at height h above the surface, and without covering we have

$$g_0 = 5510 \cdot G \cdot \frac{4 \pi}{3} \frac{R^3}{(R+h)^2} \ \ \ \ \ \ \ \ \ \ \ \frac{m}{s^2}$$

(5510 $\frac{kg}{m^3}$ being the mean density of the Earth, other symbols taking their usual meanings). The rate of change just above the surface is $$-2 \cdot 5510 \cdot G \cdot \frac{4 \pi}{3} \ \ \ \ \ \ \ \ \ \ \frac{m}{s^2m}$$ The rate of change of g at the surface of sphere with covering density $ \rho$ must then be $$3 \cdot \rho \cdot G \cdot \frac{4 \pi}{3} \ \ \ \ \ \ \ \ \ \frac{m}{s^2m}$$ It seems that the uniform surface covering must have a density more than 2/3 of the mean density of the Earth beneath it if gravity is to increase. This would be a rock with specific gravity of more than 3.67 if there is to be any chance that the gravity at the top of the "mountain" exceeds that at the bottom. The S.G. of the densest basalt is less than 3.1, and granite is even lighter (below 2.8).

This means that there is no realistic chance that a mountainous coating could result in an increase in gravity.

So the situation where hills/mountains might provide gravitational increases would be where we have steep inclines rising out of deep sea, as these provide an increase in density at levels below the sea-level surface. They would still not provide increases above standard gravity unless the total crust thickness in the region was less than average.

A map of measurements can be found here.

This appears to show that some of the highest values are found in the Andes and in parts of the Hymalayas.

I find this more than unexpected, so I suspect that this is the gravity referenced to some fixed height above sea-level rather than the surface gravity.

Jack Black's answer using a small sphere outside the surface seemed to me too extreme to establish the maximal case for real hills. It seems to me that an extreme model that looked at the maximum effect of a non-equilibrium covering be more definitive. So I have looked at the effect of a "mountain" that was so wide that it could be treated as a covering of uniform thickness across the entire globe.

Taking the field of the Earth at height h above the surface, and without covering we have

$$g_0 = 5510 \cdot G \cdot \frac{4 \pi}{3} \frac{R^3}{(R+h)^2} \frac{m}{s^2}$$

(5510 $\frac{kg}{m^3}$ being the mean density of the Earth, other symbols taking their usual meanings). The rate of change just above the surface is $$-2 \cdot 5510 \cdot G \cdot \frac{4 \pi}{3} \frac{m}{s^2m}$$. The rate of change of g at the surface of sphere with covering density rho must then be $$3 \cdot \rho \cdot G \cdot \frac{4 \pi}{3} \frac{m}{s^2m}$$.

It seems that the uniform surface covering must have a density more than 2/3 of the mean density of the Earth beneath it if gravity is to increase. This would be a rock with specific gravity of more than 3.67 if there is to be any chance that the gravity at the top of the "mountain" exceeds that at the bottom. The S.G. of the densest basalt is less than 3.1, and granite is even lighter (below 2.8).

This means that there is no realistic chance that a mountainous coating could result in an increase in gravity.

So the situation where hills/mountains might provide gravitational increases would be where we have steep inclines rising out of deep sea, as these provide an increase in density at levels below the sea-level surface. They would still not provide increases above standard gravity unless the total crust thickness in the region was less than average.

A map of measurements can be found here.

This appears to show that some of the highest values are found in the Andes and in parts of the Hymalayas.

I find this more than unexpected, so I suspect that this is the gravity referenced to some fixed height above sea-level rather than the surface gravity.

Jack Black's answer using a small sphere outside the surface seemed to me too extreme to establish the maximal case for real hills. It seems to me that an extreme model that looked at the maximum effect of a non-equilibrium covering be more definitive. So I have looked at the effect of a "mountain" that was so wide that it could be treated as a covering of uniform thickness across the entire globe.

Taking the field of the Earth at height h above the surface, and without covering we have

$$g_0 = 5510 \cdot G \cdot \frac{4 \pi}{3} \frac{R^3}{(R+h)^2} \frac{m}{s^2}$$

(5510 $\frac{kg}{m^3}$ being the mean density of the Earth, other symbols taking their usual meanings). The rate of change just above the surface is $$-2 \cdot 5510 \cdot G \cdot \frac{4 \pi}{3} \frac{m}{s^2m}$$ The rate of change of g at the surface of sphere with covering density $ \rho$ must then be $$3 \cdot \rho \cdot G \cdot \frac{4 \pi}{3} \frac{m}{s^2m}$$ It seems that the uniform surface covering must have a density more than 2/3 of the mean density of the Earth beneath it if gravity is to increase. This would be a rock with specific gravity of more than 3.67 if there is to be any chance that the gravity at the top of the "mountain" exceeds that at the bottom. The S.G. of the densest basalt is less than 3.1, and granite is even lighter (below 2.8).

This means that there is no realistic chance that a mountainous coating could result in an increase in gravity.

So the situation where hills/mountains might provide gravitational increases would be where we have steep inclines rising out of deep sea, as these provide an increase in density at levels below the sea-level surface. They would still not provide increases above standard gravity unless the total crust thickness in the region was less than average.

A map of measurements can be found here.

This appears to show that some of the highest values are found in the Andes and in parts of the Hymalayas.

I find this more than unexpected, so I suspect that this is the gravity referenced to some fixed height above sea-level rather than the surface gravity.

Jack Black's answer using a small sphere outside the surface seemed to me too extreme to establish the maximal case for real hills. It seems to me that an extreme model that looked at the maximum effect of a non-equilibrium covering be more definitive. So I have looked at the effect of a "mountain" that was so wide that it could be treated as a covering of uniform thickness across the entire globe.

Taking the field of the Earth at height h above the surface, and without covering we have

$$g_0 = 5510 \cdot G \cdot \frac{4 \pi}{3} \frac{R^3}{(R+h)^2} \frac{m}{s^2}$$

(5510 $\frac{kg}{m^3}$ being the mean density of the Earth, other symbols taking their usual meanings). The rate of change just above the surface is $-2.5510 \cdot G \cdot \frac{4 \pi}{3}$. The rate of change of g at the surface of sphere with covering density rho must then be $3 \cdot \rho \cdot G/4/3\pi$.

It seems that the uniform surface covering must have a density more than 2/3 of the mean density of the Earth beneath it if gravity is to increase. This would be a rock with specific gravity of more than 3.67 if there is to be any chance that the gravity at the top of the "mountain" exceeds that at the bottom. The S.G of the densest basalt is less than 3.1, and granite is even lighter (below 2.8).

This means that there is no realistic chance that a mountainous coating could result in an increase in gravity.

So the situation where hills/mountains might provide gravitational increases would be where we have steep inclines rising out of deep sea, as these provide an increase in density at levels below the sea-level surface. They would still not provide increases above standard gravity unless the total crust thickness in the region was less than average.

A map of measurements can be found here.

This appears to show that some of the highest values are found in the Andes and in parts of the Hymalayas.

I find this more than unexpected, so I suspect that this is the gravity referenced to some fixed height above sea-level rather than the surface gravity.

Jack Black's answer using a small sphere outside the surface seemed to me too extreme to establish the maximal case for real hills. It seems to me that an extreme model that looked at the maximum effect of a non-equilibrium covering be more definitive. So I have looked at the effect of a "mountain" that was so wide that it could be treated as a covering of uniform thickness across the entire globe.

Taking the field of the Earth at height h above the surface, and without covering we have

$$g_0 = 5510 \cdot G \cdot \frac{4 \pi}{3} \frac{R^3}{(R+h)^2} \frac{m}{s^2}$$

(5510 $\frac{kg}{m^3}$ being the mean density of the Earth, other symbols taking their usual meanings). The rate of change just above the surface is $$-2 \cdot 5510 \cdot G \cdot \frac{4 \pi}{3} \frac{m}{s^2m}$$. The rate of change of g at the surface of sphere with covering density rho must then be $$3 \cdot \rho \cdot G \cdot \frac{4 \pi}{3} \frac{m}{s^2m}$$.

It seems that the uniform surface covering must have a density more than 2/3 of the mean density of the Earth beneath it if gravity is to increase. This would be a rock with specific gravity of more than 3.67 if there is to be any chance that the gravity at the top of the "mountain" exceeds that at the bottom. The S.G. of the densest basalt is less than 3.1, and granite is even lighter (below 2.8).

This means that there is no realistic chance that a mountainous coating could result in an increase in gravity.

So the situation where hills/mountains might provide gravitational increases would be where we have steep inclines rising out of deep sea, as these provide an increase in density at levels below the sea-level surface. They would still not provide increases above standard gravity unless the total crust thickness in the region was less than average.