Are survey distances horizontal, or do they measure the lay of the land.

I’m trying to find the rear corner of my lot. The plat says the back corner is 120’ from the front stake (which I’ve located). But the lot slopes down at a 15 to 20-degree angle.

So do I anchor my 120’ line on the front stake and look for the back corner stake (follow the lay of the land)? Or do I mark out 124’ to 127’ on my line (120’ horizontal)?

Under either scenario the back stake is in heavy brush and undergrowth – hence my desire to narrow the area I have to search.

Horizontal/Level
.

The old joke goes “Idaho is the biggest state in the Union, if you lay it out flat”.

There may or may not be a stake there. In my case, three of the four corners of my lot have no markings. The one that has a pipe sticking out may or may not be precisely positioned. The nearest two stone bounds are over 400 feet from my property lines and I live in development with one acre lots.

markers can be buried to prevent disruption. there can also be an above ground marker (metal on a tree for example) in the near location of buried marker.

All distances recorded on a survey map are horizontal.
You can measure slopes in shorter segments and add them up.
Use a plumb line, or any convenient straight object…a ski pole,a curtain rod, a hiker’s walking stick, etc.
It ain’t difficult:
Walk downhill unrolling the tape keeping your end of the tape at the same height as the starting point. As you go downhill, you reach a point where the tape is at the same level as the top of your walking stick. Hold the stick plumb, and mark that spot on the ground, the bring the tape forward and measure the next segment.

But if you are planning to do anything major, like build a fence, don’t rely on an old pipe and a stone that you think might be the property corner. Hire a land surveyor to make sure you dont accidently encroach on your neighbor’s lot.