Kewaneh & Shark

The benchmarks are survey monuments and surveyors use metal locators all the time for finding them. Often times, if the mark hasn't been visited in a while, or it's in a location where the ground cover piles up, they do get covered, and a metal detector and shovel may be the only way to find them. I've been to benchmarks where the description says it's up 6" above the ground, or flush with the ground, and found them covered by 6" of hardpacked dirt! (Those are the ones that haven't been visited in a LONG time.) The detectors used by surveyors are specialized for finding benchmarks, property corners, underground utilities, and such, but any inexpensive metal detector from an sporting goods store (or Ebay) would probably do the trick for finding that benchmark that's hiding just out of view. However, if the benchmark had been set years ago, like 100 years or more, the mark may be something other than metal - like a rock. At this point, the metal detector is useless. (duh) ...but the shovel still works. Read the description for the benchmark, know what you are looking for, and enjoy the hunt. Keep on Caching! - Kewaneh

What happens to a benchmark is determined by the the agency that governs that particular benchmark, if they know that something is being done with it. As a general rule, benckmarks are/were placed in areas that are relatively safe & stable for the mark, however, what was safe & stable 30, 60, or 90 (or more) years ago may not be any more. If there is construction happening near the benchmark, and the mark is in the way, it may be relocated if it is determined that the mark is still of some use or necessary. It may be necessary to move the construction, too. The govering agency may determine that the BM is of little or no value, or it may have moved by natural or manmade forces, and may decide to remove it altogether. Over time, some benchmarks just get abandoned or destroyed, and even though the agency stil has the data, the mark is gone. I recently logged a benchmark (gt1657) that had some construction done nearby some years back. Originally, the brass cap was located on the northeasterly corner of a rural intersection in a rock outcropping. Use of the roads made the construction of a more user-friendly intersection necessary. The location of the benchmark was spared and the intersection was moved to the north. The cap and rock outcropping are now on the southeasterly corner of the intersection. The most recent (1972) NGS description has not been updated - it still has the cap 62 feet north of the road. - Kewaneh