On Fri, 07 Jan 2005 16:49:29 +0000, Mike Causer
wrote:

On Fri, 07 Jan 2005 16:30:34 +0000, Gavin Staples wrote:

Thanks very much Mike. I am interested to know the altitude (ASL) of my
home village of Horseheath, South Cambs.

There's a spot-height at the T-junction in the middle of the village (with
phone box) at 93m AMSL. The church is on the 95m contour, and the 100m
contour crosses the old Cambridge - Haverhill road at the junction with
the bypass to the east, and just at the end of the houses to the west.

You should be able to interpolate to about a metre with luck.

While I've got the map out, the spot height is pretty close to 56:06:00N
00:21:10E (do not trust Mapquest et al. for Lat & Long!)

Interpolation usually works, of course, but you do need to apply local
knowledge and allow for any discontinuities.

There are some low cliffs/steep slopes near me at Hillhead (Solent) of
around 10m height, with a large plateau at the top. Houses along the
clifftop road appear at first sight to be down at sea level and in
danger from unusually high tides but in reality, they are quite safe
as they are up around 9 to 10m amsl. The 10m contour is about 400m
inland and interpolation used in some digital OS based maps (such as
Memory Map) produces a significant error in the digital readout of
height above sea level. It's especially significant on the coast!

--
Dave