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Post by oleruns on Sept 24, 2006 11:37:56 GMT -9
NorthWes would be the man on that question. If he doesn't reply, send him an email.
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Post by ladybugkids on Sept 24, 2006 13:19:59 GMT -9
Give Northwes a week or so unless he can find a wireless spot. He's running around Arizona and Nevada for awhile.
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Post by NorthWes on Oct 6, 2006 10:51:15 GMT -9
I'm back (after finding 24 benchmarks while on the road in the Southwest), I'm almost caught up at work, and I'm diving into our fabulous geocachealaska.org forums! There's two ways to search the gc.com database to see if the disk you've found ('recovered' in benchmarking lingo) is loggable as a 'find' from the 'find a benchmark' page. If it's near a geocache, click on the geocache page's 'find all nearby benchmarks' link and see if a listing that matches the mark's description is shown (not so much the exact coordinates, as those are just estimated on the older marks placed in pre-GPS days, but based on its exact face markings or 'stamping'). Or, you can enter the coordinates of the find and search by that method. Generally speaking, if it's a disk (bronze or aluminum) with the word 'cadastral' on it, it's not going to be in the NGS database that's loaded to the geocaching.com website. You can put it up for a waymark find, but the database loaded on the geocaching.com site lists what are called 'geodetic control points' - used to establish more than property lines and corners in two dimensions (which is what most cadastral survey markers are placed to accomplish). Cadastral survey marks are very common (and often overlooked), and are sometimes logged in other databases (for example, there's an online list of all the points the Muni of Anchorage has 'registered' as survey control points - it's somewhat useful when searching for gc.com loggable benchmarks... sometimes). For more info go to the gc.com's FAQ link for Benchmarks (and if you're really intrigued, dive into the forums about Benchmarking on the gc.com website). Here's that link: www.geocaching.com/mark/
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Post by Malcore on Oct 6, 2006 17:15:09 GMT -9
I know nothing about the bench marks but I have seen a few in my travels. What im wondering is, is there a way to know when your in the field and looking at a benchmark if it is a 'geodetic control points' and maybe listed on the site. Heres an example. When I was looking for the cache 'GCXPPO Summit View' I found a benchmark with the markings 'AK Dot Hatcher 5 2001'. But when I looked for it on the web site it wasn't there.
Just courious
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Post by NorthWes on Oct 12, 2006 9:19:35 GMT -9
Malcore, the first plan I use to help in this situation is to pre-survey (pardon the pun!) the target cache zone for nearby benchmarks from the database, using the 'find nearby benchmarks' option on the cache listing page. If I find any nearby ones I load a .loc file into GSAK, and then edit that file's description to include ALL the directional data (if there's no handheld GPS coordinates posted for the EXACT location). I then take that file and flip it into Cachemate & put it on my PDA, together with a waypoint for the exact or estimated position onto my GPS (through Mapsource).
Now, in the field, if you encounter a random benchmark and want to know if it's loggable, the first clue is its headstamp. MOST loggable marks are placed by the NGS or NOAA. However, there are a few municipal marks (usually stamped GAAB XX) which are loggable - and they're usually mounted vertically on the side of buildings. (Remember - for every 'usually' there's a dozen different examples!). A few of the US Corps of Engineer marks are loggable (but oddly, in Alaska, not most of them); some private surveyor - placed marks are loggable too. In general though it's the big bronze NGS - type disks that net a 'find'. And, in every case, when you think you have a loggable find you must match the headstamp to the description!
Best local example of a commonly mis-logged benchmark where folks don't confirm the headstamp is the benchmark located near Dalli Lambda cache, between the cache & the parking area, stamped DOT PF GPS24 1989 at N60 59.074 W149 36.494. Lots of folks have logged this as a find, when in fact the only loggable nearby benchmark is TT0446 (stamped F73 1964), which is located across the highway on the north side of the road, about 22' higher than the roadbed, on an outcropping of rock. It's easy to find, but not nearly as obvious as the newer benchmark at highway grade near the parking area.
I always photograph the disk & take a GPS coordinate for any mark I find, and add it to a Mapsource database I try to keep updated with random benchmarks that aren't loggable.. This winter I may toy with putting them into Waymarking.com, when the snow is deep and the temps are low...
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Post by Malcore on Oct 13, 2006 21:28:52 GMT -9
It sounds like there is a lot of different types of benchmarks. I guess thats one of the chalanges to the finding of these. I have another question or two. After reading a bunch of discreptions of benchmarks that are loged on the web site, I noticed that many haven't been found sence they were placed in the early 40's. Have you noticed if the ones in the wooded areas are all grown over and not findable or are they placed where they wont get covered by the 60 years of growth sence they were placed. Also I read one that the discreption says its placed a few inches BELOW the ground level. How would you find that kind?, with a metal detector?
P.S. I found that there are some benchmarks placed by moose creek at what once was a train station. that would be a interesting place to try and find.
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Post by NorthWes on Nov 4, 2006 8:41:40 GMT -9
In wooded areas you're really fortunate to find a 'low-mount' benchmark if it hasn't been recovered in the past few years, whether you use a metal detector or not. First problem is that those older marks are usually 'scaled' locations, so unless there's an excellent unchanging still-recognizable landmark referenced nearby you will be searching blind with little or no help from a GPS. Secondly, many of the 1940-era benchmarks are war relics - placed by an Army engineering battalion (you can see their name on the datasheet) with the general intent of providing reference points for artillery spotting; occasionally they placed marks for assisting with commerce (roads/railways/ports), but you'll notice most 1940s marks are around 1-2,000 feet up on the side of the mountain, on a distinctive knob or ridge. They'd be fun to search for - but they always seem to be in nasty places to access! I asked an Army artillery officer about this practice - he remarked that was part of the defence plan for Alaska in the forties - the Army prepared for an invasion that ended up never happening, with forts/marks/trails around southcentral Alaska that never needed to be used.
Now, in many cases there's a notation in a benchmark listing that indicates a buried mark, with an additional surface mark. This was done to provide a near-indestructible subsurface point that could be used to re-establish the surface mark if it was accidentally damaged. We log only the surface marks... don't try digging up a subsurface marker! It's ok to excavate a bit for a mark that's been covered by dirt/sod/debris - but do it carefully so you can restore the area exactly as it was. Many mark hunters carry long metal probes to 'fish' for buried surface markers. I've had to clean a lot of debris off markers on bridge abutments & along roadways. This is a reason more recent markers are placed inside 'tubes' with a cover hatch. A good example of this is the marker in front of the Mat-Su borough offices - you access it by opening a 6" hatch. The newest marks have a hatch, and an extendable 'mast' that is carefully pulled up out of the hole. We should never extend a marker - leave that for professional surveyors. Many newer marks have the designation stamped in a ring around the hatch cover - a photo of that suffices to document the find.
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Post by Malcore on Nov 4, 2006 10:40:26 GMT -9
Thats some great info and helps me figure out if I well want to go after a benchmark after reading the listings on it. The one that I read about being buried is on the top of a mountain and looked like it might be accessable by ATV so that might be a fun one to find next summer. As for the ones I read about that are by moose creek, they refrenced a water tower nearby, but I dought that the tower is still there. So as you say they may be hard to find. But I think I will still go try finding them. The railroad path should be still there and that should help. Although I will probibly have to wait till summer to try getting into this. Im just not setup to go tramping therw the snow and cold. ;}
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Post by NorthWes on Nov 4, 2006 18:30:00 GMT -9
Man - I know just what you mean about the snow. Got out with my daughter Johns_gatorgirl and ran down a half-dozen caches today... but I wouldn't have looked for a single benchmark under the snow! No - this is the time of year when a trip to Arizona sounds like the perfect benchmarking (and geocaching) vacation!
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Post by whardier on Jun 16, 2007 20:53:09 GMT -9
picasaweb.google.com/whardier/Geocaching/photo#5076856472519448818thats what you found, right Malcore? Either way I see tons of survey marks all over the place lately.. lots I have to look up and figure out what to do with Lots downtown and lots in the middle of the streets around Anchorage. the B.L.M. mark in the link above is just west of the Bird Creek cache. I wish I could easily just log all the marks I see all over the place - probably 15 or so at this point.. They are mostly private survey companies.. Northwes you are on my "to bug" list for benchmarking - I may owe you some beer at some point to pick your brain. - wharider
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Post by NorthWes on Jul 2, 2007 11:21:52 GMT -9
Sounds almost like we need an event where we do a benchmarking component, eh? There's a lot of cadastral survey markers out there... more by far than the 'loggable' ones, although many which are found are loggable with the NGS even though they're not loggable on the gecoaching.com website...
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Post by Malcore on Jul 2, 2007 20:10:17 GMT -9
An event would be great. i would love to learn more how to do benchmarking.
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