The following article by David Strange originally appeared in The Courier-Journal on 8 May 2013. It is archived here with additional information for your reading enjoyment.
Some of them are hiding in plain sight.
In fact, you might well have passed within a few feet of one every day for years as you went to work, and simply never noticed it.
Others can be very hard to find, placed high up on hilltops or driven deep into the ground, unintentionally providing a challenging game for hobbyists known as "benchmark hunters."
But I bet you that every land surveyor worth his salt knows them well.
Also known as geodetic marks, bench marks, and trig points, among other names, these little brass discs might seem unimportant. But every person reading this story is mightily affected by them in one way or another.
An easy example of one of these markers that you can see, pictured here, is on the foundation of the Bullitt County Courthouse.
It doesn't look like much and is only a few inches in diameter. But it is THE reference point for the flood plain in our area. Want to build a house or a subdivision? To get financing or insurance, or even a permit to build? You will probably have to prove that the property won't flood. A surveyor will start at that key reference marker and measure from there.
It's up to the marker if you will pass.
County Surveyor, John St Clair, tells me that there are thousands of such survey markers all over the country, and a couple dozen in Bullitt County alone; more if you count various state markers. The markers are maintained by the federal government as part of the National Geodetic Survey (NGS) program, which reruns the points every twenty to thirty years, or as needed, to maintain them, and update accuracy.
These are the gold-standard reference points for surveyors, upon which all our property lines, construction plans, and drainage projects are ultimately based.
The marker at the courthouse, designated as BM 31-K, or 31K1928, was placed there in 1928. Eighty-five years ago. It was revisited in 1942, 1983, and again in 1988. The construction of Taylorsville Lake allowed the flood plain elevation at Shepherdsville to be lowered by a couple of feet.
That reference marker, by the way, is 449 feet above relative mean sea level, if you were curious.
Other markers can be found at Bardstown Junction, in Mt. Washington near the McFarland-Troutman-Proffitt Funeral Home, and in the hilltops, such as a knob south of Salt River.
Markers are usually brass, like the one at the courthouse, but some are in concrete, or cut into rock, and some are set deep in the ground in a capped hole. John St Clair tells me that, if you know where to look, you will see fiberglass poles in some areas, about four or five feet tall. Those poles are set near a brass marker as a "witness," to help prevent bush-hogs and other equipment from disturbing the marker. But they can help you find them, as well.
Let me mention here that Mr. St Clair has faithfully filled the office of Bullitt County Surveyor for a number of years now. I point this out because that office, somewhat like the survey markers, often goes unnoticed by many. It is an elected office, voted on by the people every four years.
I asked him about the hobby of "benchmark hunting." That increasingly-popular hobby involves using geocaching technology to go out in search of the survey markers, just for the challenge of finding them. Mr. St Clair just asks that everyone please not disturb or damage the markers. In fact, I read that the markers are protected by both state and federal law. If you get into such a hobby, you should also remember that many of these markers are on private land or in dangerous locations such as the edge of a cliff.
For more information on the hobby, you might want to check the internet at www.geocaching.com/mark/default.aspx.
You can also find a map of some of these points on the Bullitt County History Museum web site on another page.
The survey marker at the courthouse is for flood-plain elevation only, but most are "trig points" or trigonometry reference points, measured very precisely from one to the other, right down to the tiny point indented into the center of the tiny triangle symbol.
I once thought that such markers, which often are placed at a Courthouse or City Hall, was the zero mark for mileage, but that is not exactly true. Have you ever wondered about that? When you see a sign saying something like "twenty miles to Shepherdsville," have you ever wondered just where, exactly, that twenty miles was measured from? After all, the borders of a city often change.
Well, the marker has nothing to do with it, but the building might. Generally, the distance to a city is measured to the main government building, or "the center of the city." That is why when you cross the Bullitt County line into Jefferson County, which is actually now the border of the "metro" city of Louisville itself, a sign on Interstate 65 says it is still twelve miles to Louisville.
It seems a little funny that such seemingly insignificant things as these brass survey markers can be so important, and in a way, even a marker of history.
But then again, I have often found that to be the case. Small things in our lives that at first might go unnoticed, often become what affects us the most.
The unseen things that are the roots of our memories.
Copyright 2013 by David Strange, Shepherdsville KY. All rights are reserved. No part of the content of this page may be included in any format in any place without the written permission of the copyright holder.