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Or, planning on a long winter, be working on organizing 20,000 plus BM & bird shots taken in the last seven years. Saw this one in 2009 -AJ3986_MARKER: DK = GRAVITY REFERENCE MARK DISK - not in GeoCache and did not do a recovery (less than a year since previous) - near Q 10. Scabbed on a photo there. Not stamped Magnetic disk also nearby. kayakbird

Guess I found a gravity station! (Though that was nine years ago!) How do I check my other 800 benchmark logs to see what other types I have found?

I put this BM on my to-do-list after reviewing my country wide datasheets seach for this type of disk. On my visit-the-family up north trip, I made my way to GZ in west central NJ, driving in a light snow storm; I don't get to see much snow down here in S. Florida. This rare new style Gravity Reference Mark from 1937 was definitely one of the easiest BM's I've recovered, right on the side of the road. It looks like a couple of the forum regulars also visited this site a few years back. PID KV1610. A nice find for anyone Benchmarking or Geocaching in the area.

No, I didn't. I guess that I should have! I think I checked the real thing from NGS by going through the search page--I was going through a list and checking for those specifically. Do you think they updated it already based on my log? When going for these, I make a point of checking the real thing through NGS. But I can't swear to the fact that I looked on the NGS site...I think I did, though. If they updated the page based on my log, I would expect to see the recovery note by a geocacher at the bottom. Very strange! The moral of the story is, check the real NGS sheet, not just what's on gc.com...but I thought I did. From the gc.com link: LF1239_MARKER: DG = GRAVITY STATION DISK LF1239_SETTING: 7 = SET IN TOP OF CONCRETE MONUMENT LF1239 LF1239 HISTORY - Date Condition Recov. By LF1239 HISTORY - 1958 MONUMENTED CGS LF1239 HISTORY - 1975 GOOD USGS LF1239 HISTORY - 1977 GOOD NGS From the NGS link: LF1239_MARKER: DS = TRIANGULATION STATION DISK LF1239_SETTING: 7 = SET IN TOP OF CONCRETE MONUMENT LF1239_STAMPING: HIGHLAND 1958 LF1239_MARK LOGO: CGS LF1239_STABILITY: C = MAY HOLD, BUT OF TYPE COMMONLY SUBJECT TO LF1239+STABILITY: SURFACE MOTION LF1239 LF1239 HISTORY - Date Condition Report By LF1239 HISTORY - 1958 MONUMENTED CGS LF1239 HISTORY - 1975 GOOD USGS LF1239 HISTORY - 1977 GOOD NGS

I'm surprised that the data sheet archived on Geocaching.com shows it as LF1239_MARKER: DG = GRAVITY STATION DISK but the current NGS data sheet has LF1239_MARKER: DS = TRIANGULATION STATION DISK while the latest recovery is the same 1977 on both. Somehow the discrepancy came to their attention. Did you submit a correction to them?

The coolest and must visit of all the USC&GS disks, the Gravity Station disk. Took a trip to Las Vegas and made the short trip to Death Valley, CA to see this one. GS0206. Took the rental down the 35 mile gravel road recovering a bunch of CGS benchmarks along the way until reaching the Dayton-Harris BM. You need a GPS for this area. It was a mild 113 degrees at 200+ ft below sea level. An awesome day trip to consider if your in the Las Vegas area. Does anyone know where else one of these has been found?

Yup! Geocaching is what you make it to be. You can go after death-defying caches on cliffs and atop abandoned bridge pillars. You can challenge yourself to 24 hours of monotony finding 2500 film canisters along a desert highway. You can take a fifteen mile hike into the mountains to find a cache nestled near a scenic lake. You can drive over to a city park and find a cache under a lampskirt.

The stamped elevation was probably within a fraction of a foot on the old NGVD29 datum, if the monument hasn't been moved. Since it's Geological Survey and not Coast & Geodetic Survey (predecessor to NGS) it might be a little looser than those on NGS data sheets. The stamped elevation could be different by several feet on the current NAVD88 datum - I haven't checked for the difference in that area. GPS of any grade does not measure elevations on either of those datums. It measures height above the mathematical ellipsoid model of the earth. That is typically several to many meters different from either of the elevations. Your handheld receiver probably has an approximate model of the difference (the geoid height) to give you a reading somewhat closer to the datums than the raw height measurement. Elevation isn't GPS's strong suit anyway, as you may notice by watching your reading wander around. Even surveyor grade GPS and the best geoid model isn't quite the same as NAVD88, but NGS is working on an improved gravity model that will let them replace NAVD88 within a few years. NAD83 is NOT exactly the same as WGS84, although the difference less than the typical repeatability of a recreational GPS so they treat them as the same. When WGS84 was defined, it and NAD83 were intended to be the same, and were to the accuracy that could be attained at the time. Now we know they are 3 or 4 feet different in the US, and growing further apart by 1.5 to 2 cm per year. Once you get to measuring things this accurately, it gets to be a headache to keep track of what you're measuring.

There are plenty of dangerous caches. When seeking them, most people are aware of the risks and take extra caution. This cache was in an illegal area. Willi had to go at night, as not to be seen. He fell through a large, gaping hole that would have been obvious during the day, or if he'd been using a flashlight. The fact that it was illegal directly contributed to his death. The fact that there are plenty others like it, and that they were published on the site, enabled the CO to hide it. Looking at the pages it's rather obvious that TPTB knew that it was illegal. The question is why were these published? If someone wants to take a chance and do that type of behavior on their own, that's fine. However, publishing illegal caches on the site puts all of the legal ones at risk. When a death occurs, people take notice and see that geocachers are openly defying the law, and it creates obstacles for the legal hides. Thousand of hours spent creating legal geocaches are at risk of getting archived if certain land managers impression is that the site if full of unsupervised delinquents. Trespassing, property damage, risky and stupid behavior... Illegal activity and unsafe activities go hand in hand. People are going to get killed doing legal caching, and there is nothing that can be done about it. If it happens during illegal activities it is more likely to occur and puts the entire game to shame. It's not mentioned in "Geocaching in the News" because it is embarrassing and shameful.

You think that someone who actually goes the ISS is going to have his experience "cheapened" because someone posted a find log because he got a picture of himself on the ISS? The going to space experience will not be cheapened, but I do think the geocaching part would be. If someone actually goes to space, do you think the geocaching part is very important anyway?? Schwwwwaaaaaaah. Like I'd go into space for some other reason?!? Puh-lease. I'd go for the zero G human fertility experiments. Hey, if we're to become a spacefaring race and get all of our proverbial eggs outta this terrestrial basket we gotta test it out.... Right? You want to get 'fertilized' in space? I'm pretty sure that even without gravity, it's not going to take. I'm pretty sure that no amount (or lack) of gravity will contribute to a sucessful fertilization of a human male or male Snoogans. But I'm no rocket surgeon.

but that wouldn't be zero gravity, that would be negative gravity. not the same thing!!

(The defacement or destruction is visible on a low res jpeg image taken from SPACE.....) but, the rules/reviewers have an issue with people wanting to honor our military veterans? Or, since the celebratory tone of the post I'm referencing... ...it almost looks like this cache series had/has an agenda of CLEARLY defying a rule, and potentially making geocaching harder for all of us by doing so, I can only assume this entire series is awaiting archival now, by one of our astute reviewers. Just a note: the person who started the thread about that series was not the owner of the series, and had hit the sarcasm juice hard that day. Yes, he/she was being very sarcastic, not serious. And no, regardless of what you think of the series, the agenda was never to "CLEARLY defy a rule". It was to create a power trail. End note.

Just making sure I understand this. We have what, three pages on a forum entry showing this rule being CLEARLY defied..... (The defacement or destruction is visible on a low res jpeg image taken from SPACE.....) but, the rules/reviewers have an issue with people wanting to honor our military veterans? Or, since the celebratory tone of the post I'm referencing... ...it almost looks like this cache series had/has an agenda of CLEARLY defying a rule, and potentially making geocaching harder for all of us by doing so, I can only assume this entire series is awaiting archival now, by one of our astute reviewers. (Damage to the environment may not be an issue at this particular location. I'm referencing the apparently selective enforcement of the rules, and what is, in my opinion, a skewed perspective on things.) I normally support the staff at Groundspeak 100%, and have even encouraged Members to pay for the premium membership. However, on this issue, I can't. And, yes, I am a military veteran, but that's irrelevant to this discussion. If someone trying to do something to honor a part of our society that is largely responsible for us having the freedom to live as we choose is shot down by a reviewer, how is the other post I'm referencing in any way condoned? Since I suppose I'm a paying customer, perhaps someone can answer me this.

I reckon about 50,000 years. I've been out of the astronomy scene for a while - last time I heard the highest speed a spacecraft has reached is about 18km/s. At that speed, and ignoring slowing down effects of the sun's gravity, it'll take around 70,000 years. I presume the Helios is somewhat faster, and a gravity assist by Jupiter will do wonders for it.

Has anybody seen a discussion of how they converted GPS height above the ellipsoid into orthometric height above the geoid? How well can they trust the geoid (gravity) model on top of a mountain that probably hasn't had a direct gravity measurement? And is it NGVD29 or NAVD88?

I'm going to reawaken this old thread to point out an article in The New Yorker's February 27, 2006, issue ("Watermark" by Elizabeth Kolbert). It's a vivid tour of the Louisiana Delta post-Katrina, and on p. 49 she mentions several bench marks where the mark itself had subsided along with the surrounding soil. C 195, for example, had subsided 9 inches. Several of the marks are now at or below sea level when it was presumed they they were at least a few inches above. I've attached the current datasheet from that mark; the others mentioned are A 152 (AT0407), C 195 (AT0458), D 194 (AT0357), and EMPIRE AZ MK 2 1934 1966 (AT0231). 1 National Geodetic Survey, Retrieval Date = APRIL 20, 2006 AT0458 *********************************************************************** AT0458 HT_MOD - This is a Louisiana Height Modernization Survey Station. AT0458 DESIGNATION - C 195 AT0458 PID - AT0458 AT0458 STATE/COUNTY- LA/PLAQUEMINES AT0458 USGS QUAD - POINTE A LA HACHE (1992) AT0458 AT0458 *CURRENT SURVEY CONTROL AT0458 ___________________________________________________________________ AT0458* NAD 83(1992)- 29 32 12.40304(N) 089 45 47.15604(W) ADJUSTED AT0458* NAVD 88 - 0.48 **(meters) 1.6 **(feet) GPS OBS(2004.65) AT0458 **This station is located in a subsidence area (see below). AT0458 ___________________________________________________________________ AT0458 EPOCH DATE - 2004.65 AT0458 X - 22,962.963 (meters) COMP AT0458 Y - -5,553,681.857 (meters) COMP AT0458 Z - 3,125,790.379 (meters) COMP AT0458 LAPLACE CORR- 0.52 (seconds) DEFLEC99 AT0458 ELLIP HEIGHT- -24.12 (meters) (06/22/05) GPS OBS AT0458 GEOID HEIGHT- -24.60 (meters) GEOID03 AT0458 DYNAMIC HT - 0.48 (meters) 1.6 (feet) COMP AT0458 MODELED GRAV- 979,303.6 (mgal) NAVD 88 AT0458 AT0458 HORZ ORDER - B AT0458 VERT ORDER - THIRD (See Below) AT0458 ELLP ORDER - FOURTH CLASS I AT0458 AT0458.The horizontal coordinates were established by GPS observations AT0458.and adjusted by the National Geodetic Survey in June 2005.. AT0458.The horizontal coordinates are valid at the epoch date displayed above. AT0458.The epoch date for horizontal control is a decimal equivalence AT0458.of Year/Month/Day. AT0458 AT0458 ** Due to the variability of land subsidence, the orthometric, ellipsoid, AT0458 ** and geoid heights are valid at the date of observation. These heights AT0458 ** must always be validated when used as control. AT0458 ** The orthometric height was determined by GPS observations using AT0458 ** precise GPS observation and processing techniques and a new AT0458 ** realization of GEOID03. It supersedes the leveled height previously AT0458 ** determined for this station. AT0458 ** The geoid height was determined by a new realization of GEOID03 for the AT0458 ** epoch indicated which incorporates improved geoid heights for the AT0458 ** Southern Louisiana Subsidence area. AT0458 ** (see www.ngs.noaa.gov/PC_PROD/GEOID03). AT0458.The orthometric height was determined by GPS observations and a AT0458.high-resolution geoid model using precise GPS observation and AT0458.processing techniques. It supersedes the leveled height previously AT0458.determined for this station. AT0458.WARNING-GPS observations at this control monument resulted in a GPS AT0458.derived orthometric height which differed from the leveled height by AT0458.more than one decimeter (0.1 meter). AT0458.The vertical order pertains to the first NAVD 88 superseded value. AT0458 AT0458.The X, Y, and Z were computed from the position and the ellipsoidal ht. AT0458 AT0458.The Laplace correction was computed from DEFLEC99 derived deflections. AT0458 AT0458.The ellipsoidal height was determined by GPS observations AT0458.and is referenced to NAD 83. AT0458 AT0458.The geoid height was determined by GEOID03. AT0458 AT0458.The dynamic height is computed by dividing the NAVD 88 AT0458.geopotential number by the normal gravity value computed on the AT0458.Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 AT0458.degrees latitude (g = 980.6199 gals.). AT0458 AT0458.The modeled gravity was interpolated from observed gravity values. AT0458 AT0458; North East Units Scale Factor Converg. AT0458;SPC LA S - 115,965.036 1,152,193.647 MT 0.99995833 +0 47 06.5 AT0458;SPC LA S - 380,461.96 3,780,155.32 sFT 0.99995833 +0 47 06.5 AT0458;UTM 16 - 3,270,643.128 232,222.832 MT 1.00048485 -1 21 46.7 AT0458 AT0458! - Elev Factor x Scale Factor = Combined Factor AT0458!SPC LA S - 1.00000379 x 0.99995833 = 0.99996212 AT0458!UTM 16 - 1.00000379 x 1.00048485 = 1.00048864 AT0458 AT0458 SUPERSEDED SURVEY CONTROL AT0458 AT0458 NAVD 88 (02/14/94) 0.705 (m) 2.31 (f) READJUSTED 3 AT0458 NAVD 88 (06/15/91) 0.760 (m) 2.49 (f) UNKNOWN 1 1 AT0458 NGVD 29 (??/??/??) 0.794 (m) 2.60 (f) ADJUSTED 1 1 AT0458 AT0458.Superseded values are not recommended for survey control. AT0458.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums. AT0458.See file dsdata.txt to determine how the superseded data were derived. AT0458 AT0458_U.S. NATIONAL GRID SPATIAL ADDRESS: 16RBT3222370643(NAD 83) AT0458_MARKER: DB = BENCH MARK DISK AT0458_SETTING: 30 = SET IN A LIGHT STRUCTURE AT0458_SP_SET: SMALL CULVERT HEADWALL AT0458_STAMPING: C 195 1964 AT0458_MARK LOGO: CGS AT0458_MAGNETIC: N = NO MAGNETIC MATERIAL AT0458_STABILITY: D = MARK OF QUESTIONABLE OR UNKNOWN STABILITY AT0458_SATELLITE: THE SITE LOCATION WAS REPORTED AS SUITABLE FOR AT0458+SATELLITE: SATELLITE OBSERVATIONS - October 06, 2005 AT0458 AT0458 HISTORY - Date Condition Report By AT0458 HISTORY - 1964 MONUMENTED CGS AT0458 HISTORY - 1970 GOOD NGS AT0458 HISTORY - 1971 GOOD NGS AT0458 HISTORY - 1984 GOOD NGS AT0458 HISTORY - 20040422 GOOD NGS AT0458 HISTORY - 20051006 GOOD NGS AT0458 AT0458 STATION DESCRIPTION AT0458 AT0458'DESCRIBED BY NATIONAL GEODETIC SURVEY 1970 AT0458'5.65 MI NW FROM PORT SULPHUR. AT0458'5.65 MILES NORTHWEST ALONG STATE HIGHWAY 23 FROM THE FIRE STATION AND AT0458'CEMETERY AT PORT SULPHUR, ABOUT 0.85 MILE SOUTHEAST OF THE ST. JUDE AT0458'CHURCH, SET IN THE TOP OF THE SOUTHEAST END OF THE NORTHWEST CONCRETE AT0458'HEAD WALL OF AN 18 INCH PIPE CULVERT WITH WING WALLS UNDER A DRIVEWAY AT0458'TO A VACANT LOT, 24.3 FEET SOUTHWEST OF THE CENTER OF THE HIGHWAY, 68 AT0458'FEET NORTHWEST OF A FIRE HYDRANT, 44 FEET SOUTHEAST OF THE CENTER OF A AT0458'SMALL GATE, 9 FEET NORTHWEST OF THE CENTER OF A DRIVEWAY AND ABOUT AT0458'LEVEL WITH THE HIGHWAY, AND 1 FOOT NORTHEAST OF A METAL WITNESS POST. AT0458 AT0458 STATION RECOVERY (1971) AT0458 AT0458'RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1971 AT0458'RECOVERED IN GOOD CONDITION. AT0458 AT0458 STATION RECOVERY (1984) AT0458 AT0458'RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1984 AT0458'RECOVERED IN GOOD CONDITION. LOT IS NOW OCCUPIED BY RESIDENCE AT AT0458'ROUTE 1, BOX 749. AT0458 AT0458 STATION RECOVERY (2004) AT0458 AT0458'RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 2004 (KLF) AT0458'THE STATION IS LOCATED IN THE COMMUNITY OF DIAMOND CENTER, ABOUT 5.5 AT0458'MI NORTHWEST OF PORT SULPHER, ON PARISH HIGHWAY RIGHT OF WAY. AT0458' AT0458'TO REACH THE STATION FROM THE POST OFFICE IN PORT SULPHER GO NORTHERLY AT0458'FOR 2.35 MI ON STATE HIGHWAY 23 TO PARISH HIGHWAY 11 ON THE RIGHT, AT0458'TURN RIGHT AND CONTINUE NORTHERLY FOR 1.55 MI ON HIGHWAY 11 TO A DIM AT0458'GRAVEL DRIVE LEFT LEADING TO A PRIVATE RESIDENCE NUMBER 24704 AND THE AT0458'STATION ON THE LEFT SET IN THE TOP OF AND NEAR THE SOUTHEAST END OF AT0458'THE NORTHWEST CONCRETE HEADWALL OF AN 18 INCH CULVERT PIPE RUNNING AT0458'UNDERNEATH THE DRIVE. AT0458' AT0458'THE STATION IS LOCATED 21.8 M NORTHWEST OF A FIRE HYDRANT, 21.8 M AT0458'EASTOF THE EAST CORNER OF THE FRONT PORCH OF HOUSE NUMBER 24704, 7.6 AT0458'M SOUTHWEST OF THE CENTER OF THE ROAD, 2.5 M NORTHWEST OF THE CENTER AT0458'OF THE DRIVE, AND ABOUT 0.1 M BELOW THE LEVEL OF THE GROUND SURFACE. AT0458'NOTE--THE STAMPING HAS BEEN MARRED AND THE 5 IN THE DESIGNATION IS NO AT0458'LONGER VISIBLE. NOTE--THE HEADWALL AND CULVERT ARE BENEATH THE AT0458'SURFACE AND NO LONGER VISIBLE. AT0458 AT0458 STATION RECOVERY (2005) AT0458 AT0458'RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 2005 (KLF) AT0458'RECOVERED AS DESCRIBED WITH THE FOLLOWING CHANGES. 7.4 M NNW OF A AT0458'WATER METER, 20.3 M NNW OF A FIRE HYDRANT, AND 0.7 M NNE OF A METAL AT0458'POST WITH WITNESS SIGN ATTACHED. NOTE--THE HOUSE PREVIOUSLY AT0458'REFERENCED TO WAS DESTROYED DURINNG HURRICANE KATRINA.

Here's a more complete list. The list of benchmark types... 01 = LONE TREE 02 = CONSPICUOUS ROCK 03 = MOUNTAIN PEAK 04 = ROCK PINNACLE 05 = ROCK AWASH 11 = PILING 12 = DOLPHIN 13 = LIGHTHOUSE 14 = NAVIGATION LIGHT 15 = RANGE MARKER 16 = DAYBEACON 17 = FLAG TOWER 18 = SIGNAL MAST 21 = AIRPORT BEACON 22 = AIRWAY BEACON 25 = RADAR ANTENNA 26 = SPHERICAL RADOME 27 = RADIO RANGE MAST 28 = LORAN MAST 41 = ANTENNA MAST 42 = RADIO/TV MAST 43 = RADIO/TV TOWER 44 = MICROWAVE MAST 45 = MICROWAVE TOWER 51 = TANK 52 = STANDPIPE TANK 53 = ELEVATED TANK 54 = WATER TOWER 55 = TOWER 56 = SKELETON TOWER 57 = LOOKOUT TOWER 58 = CONTROL TOWER 61 = POLE 62 = FLAGPOLE 63 = STACK 64 = SILO 65 = GRAIN ELEVATOR 66 = WINDMILL 67 = OIL DERRICK 68 = COMMERCIAL SIGN 69 = REGULATORY SIGN 70 = MONUMENT 71 = BOUNDARY MONUMENT 72 = CAIRN 73 = LOOKOUT HOUSE 74 = LARGE CROSS 75 = BELFRY 81 = GABLE 82 = FINIAL 83 = FLAGSTAFF 84 = LIGHTNING ROD 85 = CHIMNEY 86 = CUPOLA 87 = DOME 88 = OBSERVATORY DOME 89 = SPIRE 90 = CHURCH SPIRE 91 = CHURCH CROSS 92 = ANTENNA ON ROOF 93 = MICROWAVE ANTENNA ON BUILDING 94 = ROOFTOP VENTILATOR 95 = ROOFTOP BLOCKHOUSE A = ALUMINUM MARKER B = BOLT C = CAP OF CAP-AND-BOLT PAIR DA = ASTRO MARKER (USUALLY A DISK) DB = BENCH MARK DISK DD = SURVEY DISK DE = TRAVERSE STATION DISK DG = GRAVITY STATION DISK DH = HORIZONTAL CONTROL DISK DJ = TIDAL STATION DISK DK = GRAVITY REFERENCE MARK DISK DM = MAGNETIC STATION DISK DO = NOT SPECIFIED OR SEE DESCRIPTION DP = BASE LINE PIER DQ = CALIBRATION BASE LINE DISK DR = REFERENCE MARK DISK DS = TRIANGULATION STATION DISK DT = TOPOGRAPHIC STATION DISK DU = BOUNDARY MARKER DV = VERTICAL CONTROL DISK DW = NOS HYDROGRAPHIC SURVEY DISK DZ = AZIMUTH MARK DISK E = EARTHENWARE POT F = FLANGE-ENCASED ROD G = GLASS BOTTLE H = DRILL HOLE I = METAL ROD J = EARTHENWARE JUG K = CLAY TILE PIPE L = ABSOLUTE GRAVITY STATION PLUG M = AMMO SHELL CASING N = NAIL O = CHISELED CIRCLE P = PIPE CAP Q = CHISELED SQUARE R = RIVET S = SPIKE T = CHISELED TRIANGLE U = CONCRETE POST V = STONE MONUMENT W = UNMONUMENTED X = CHISELED CROSS Y = DRILL HOLE IN BRICK Z = SEE DESCRIPTION John

I did a reply, I don't know why it didn't show up. Well, it was just two that I saw a picture of somewhere, they were NGS, not USGS. I tried by designation, but it didn't find anything. One was a gravity mark, one was a regular mark. I don't know the state they were.from.

The Coast & Geodetic Survey began long ago finding elevations of bench marks and latitude/longitude of other points (loosely called benchmarks here but not by professionals). In the 1930's a major push was made to connect the whole country into one elevation network and one lat/lon network so everybody was working off the same system. Elevation measurements require setting up an instrument about every 200 yards, reading the height on a rod behind, and the height of a rod ahead (oversimplified). Then the level instrument is moved up and the process repeated. This means it was easiest to follow a reasonably level path without excessive vegetation, and railroads and roads were the obvious paths to use. For horizontal lat/lon, most of the measurement was done by theodolites taking angles to various positions in all combinations, with typical sight lines of a few to 20 miles. The obvious places were hilltops, with additional sights to "intersection stations" like towers and water tanks. The primary network maps look like a fish net stretched across the country. Your highway happened to fall close to where they wanted a path in the mesh. After the field measurements were done, it took years of manual computation to tie all the data together into the best estimate of all the elevations and positions. Somewhere on the ngs web site under About NGS/history you can find stories and pictures of the history of these operations and maps of the progress. Today the elevation bench marks remain very important reference points for all types of construction, drainage, and flood control work. GPS cannot yet adequately replace them because GPS knows almost nothing about variations in gravity from place to place and elevation is based on gravity (it is preferred if water runs downhill). Horizontal marks are less important than they used to be, but are sometimes still useful and certain selected ones are very important references for the whole network.

Permethrin is synthesized from the natural insecticide in marigolds. That by itself wouldn't be enough to give me warm fuzzies about it, but from what I've read, I'll take that risk over the risk of Lyme disease or other tick-born infections. The thing is, permethrin is actually a toxin to ticks, not merely a repellant. I have put live ticks on a piece of fabric inside of a circle that I had soaked with a DEET-based repellant and had them totally ignore it and walk right through it. If they tried that with permetrin-treated clothing, they would be dead. Wikipedia's entry on human toxicity of permethrin: https://en.wikipedia...#Human_exposure I'm just not keen on putting stuff like this on me. I have no idea what long term effects permethrin might have and i'm fairly certain no one else does either. I'll take my chances with the ticks. We just got back from an Arkansas trip where we hiked trails in some of the state parks. Needless to say, ticks, red bugs, and poison ivy were everywhere. Picked up plenty of ticks, have a teensy bit of itching from the red bugs, and so far, haven't had the pi break out. I figure this is just part of the overall experience. Have you known anybody that had a long-term case of Lyme? I have a friend that had an eye bulging out of its socket. I've known people that didn't go outdoors for years because of it... it hurt to move. It is some baaaad stuff. Suit yourself, of course, but know the risks. Long term effects of Lyme are well-known. I had a girlfriend who got Lyme and it messed her up so bad she ended up (along with other problems) Killing herself. The pesticide is much better then Lyme disease for sure! I have been doing pest and termite control for almost 17 years. I am in no way chemical shy but also have a bunch of exposure to it. That is the reason I don't really see myself wearing Perethrin soaked clothes. I am sure if you soak it in the stuff it would take more heat then a dryer to break it all down but was just trying to figure out what the OP might be worried about. For myself for tick control I spray my boots and outer pants with some deet spray before caching somewhere I think there might be ticks. If I know tick are there I might spray more of my clothes. Good point about boots. I also treat my boots with permethrin. You had a girlfriend that ended her life, you believe in part to Lyme disease, yet you resist the only effective known deterrent? Deet simply does not slow those parasites down. You can't repel them... they aren't smart enough. DEET works by messing with your CO2 signals when it comes to mosquitoes, but ticks simply climb upwards. To the top of grass, to your chest. CO2 doesn't seem to have as much to do with it as gravity does. The long term tests are in: Lyme: Extremely serious. Permethrin: Unknown. Of course, you may never be bitten by a Lyme (or Rocky Mountain Fever or other tick-borne disease) bearing tick if you wear Permethrim-treated clothing every time you're in tick country. So it really is impossible to weigh the risks completely. But me... I'm gonna take my chances with the marigolds.

The contest is ready to begin. The rules are simple. The judges are just a couple of oldfarts. The prize is winner's choice of either "1 year premium membership to Geocaching" or "we will pay Clyde for your copy of GSAK". The rules - 1) The contest will run for 2 months, Nov & Dec.(Actually it will end on Jan 2nd since we will be on vacation prior to that time.). This will give you 2 months to acquire the documentation for as many different types as possible, (from the list at the bottom of this post). 2) You must have photographic documentation that includes the photographic image of the Geodetic Interactive Spatial Referencing Device (GISRD) and your monitoring device that shows your temporal position in the space time continuum in relation to the center of your planet. If the position can not be read on your monitoring device, the log will be voided and not count in the final tally! 3) Only 1 of each type of GISRD will be allowed per player. More than one player may log a specific GISRD. 4) Only recoveries after the start will be counted in the tally. This will start everyone on an even playing field. 5 We will have a thread where you can post a link to the PID# of those you have found. (Try to post your finds in groups to help make it a bit easier to keep track of your finds.) Please let us know which type of mark you are submitting. (As in PID# GQ0323 = V = stone monument, PID# GP0572 = 21 = airport beacon, PID# FS0759 = Q = chiseled square) 6) You may revisit previous finds and include them in your competition list of types. (Make sure your GPSr shows the date to get credit for it, though) The marker type is listed just below the designation on the GC.com datasheets. Here is a link to a thread where we described how we use GSAK to find the different types in our area. Sorting marker types Feel free to use what ever sorting method you prefer to get you the highest number of marker types. You may log the GISRD on GC.com as a note if you have previously found that particular one (so we will have a link on the thread instead of a complete log.). Any questions? #2 rules translates as "a picture showing the benchmark and your GPSr (showing the date). Good luck & have fun, John & Shirley The list of benchmark types... 01 = LONE TREE 02 = CONSPICUOUS ROCK 03 = MOUNTAIN PEAK 04 = ROCK PINNACLE 05 = ROCK AWASH 11 = PILING 12 = DOLPHIN 13 = LIGHTHOUSE 14 = NAVIGATION LIGHT 15 = RANGE MARKER 16 = DAYBEACON 17 = FLAG TOWER 18 = SIGNAL MAST 21 = AIRPORT BEACON 22 = AIRWAY BEACON 25 = RADAR ANTENNA 26 = SPHERICAL RADOME 27 = RADIO RANGE MAST 28 = LORAN MAST 41 = ANTENNA MAST 42 = RADIO/TV MAST 43 = RADIO/TV TOWER 44 = MICROWAVE MAST 45 = MICROWAVE TOWER 51 = TANK 52 = STANDPIPE TANK 53 = ELEVATED TANK 54 = WATER TOWER 55 = TOWER 56 = SKELETON TOWER 57 = LOOKOUT TOWER 58 = CONTROL TOWER 61 = POLE 62 = FLAGPOLE 63 = STACK 64 = SILO 65 = GRAIN ELEVATOR 66 = WINDMILL 67 = OIL DERRICK 68 = COMMERCIAL SIGN 69 = REGULATORY SIGN 70 = MONUMENT 71 = BOUNDARY MONUMENT 72 = CAIRN 73 = LOOKOUT HOUSE 74 = LARGE CROSS 75 = BELFRY 81 = GABLE 82 = FINIAL 83 = FLAGSTAFF 84 = LIGHTNING ROD 85 = CHIMNEY 86 = CUPOLA 87 = DOME 88 = OBSERVATORY DOME 89 = SPIRE 90 = CHURCH SPIRE 91 = CHURCH CROSS 92 = ANTENNA ON ROOF 93 = MICROWAVE ANTENNA ON BUILDING 94 = ROOFTOP VENTILATOR 95 = ROOFTOP BLOCKHOUSE A = ALUMINUM MARKER B = BOLT C = CAP OF CAP-AND-BOLT PAIR DA = ASTRO MARKER (USUALLY A DISK) DB = BENCH MARK DISK DD = SURVEY DISK DE = TRAVERSE STATION DISK DG = GRAVITY STATION DISK DH = HORIZONTAL CONTROL DISK DJ = TIDAL STATION DISK DK = GRAVITY REFERENCE MARK DISK DM = MAGNETIC STATION DISK DO = NOT SPECIFIED OR SEE DESCRIPTION DP = BASE LINE PIER DQ = CALIBRATION BASE LINE DISK DR = REFERENCE MARK DISK DS = TRIANGULATION STATION DISK DT = TOPOGRAPHIC STATION DISK DU = BOUNDARY MARKER DV = VERTICAL CONTROL DISK DW = NOS HYDROGRAPHIC SURVEY DISK DZ = AZIMUTH MARK DISK E = EARTHENWARE POT F = FLANGE-ENCASED ROD G = GLASS BOTTLE H = DRILL HOLE I = METAL ROD J = EARTHENWARE JUG K = CLAY TILE PIPE L = ABSOLUTE GRAVITY STATION PLUG M = AMMO SHELL CASING N = NAIL O = CHISELED CIRCLE P = PIPE CAP Q = CHISELED SQUARE R = RIVET S = SPIKE T = CHISELED TRIANGLE U = CONCRETE POST V = STONE MONUMENT W = UNMONUMENTED X = CHISELED CROSS Y = DRILL HOLE IN BRICK Z = SEE DESCRIPTION

Technically, the acceleration due to gravity will be less at a higher altitude than a lower one. This is because of the fact that the gravitational pull between two objects is inversely proportional to the square of the distance between them. Because the distance is measured from the center of gravity (the center of the earth), small distances above the surface have a very limited impact on the acceleration and are generally ignored in simple physics. An object placed above the surface of the earth by an amount equal to the radius of the earth would double the distance, thereby quartering the acceleration. Given that the mean radius of the earth is 6371km, and the acceleration due to gravity is accepted to be 9.82m/s/s at sea level, the acceleration, even at the top of Mount Everest (8850m), would still be 9.79m/s/s. By the way, that part of it has nothing to do with the viscosity of the atmosphere ("thinner" air) and would hold true even if there were no atmosphere at all.

If you could follow the actual level surface, which would be the surface of a lake at that height with no waves, you would not be path dependent. When you sight at something distant enough that its vertical doesn't match your vertical, or that of points in between, or where the gravity changes between your sights even if the vertical is the same, then you have another source of observation error. That error can be decreased by shortening your sights (unless the accumulation of instrument-related errors gets to you). This source of observation error depends not only on the path but also the choice of points along that path sighted on. If you run the sights by different lengths along the same path, or by a different path, the variations may cause different observation errors. It is my semi-educated guess that these gravity variation/change in vertical effects only show up in very precise surveys many miles long. If you run the same stations in the reverse direction there is no [different] error introduced by the gravity/vertical anomalies, just a new set of temperature/refraction/plumbing/etc. errors.

For the purpose of the contest, I have decided to ignore these (unless you want to put in a category for them...) Was trying to decide what to do about this one. It's in the NGS, but not in geocaching. How could I log it for the contest? DF7147 DESIGNATION - HOPATCONG DF7147 PID - DF7147 DF7147 STATE/COUNTY- NJ/MORRIS DF7147 USGS QUAD - STANHOPE (1981) DF7147 DF7147 *CURRENT SURVEY CONTROL DF7147 ___________________________________________________________________ DF7147* NAD 83(1996)- 40 55 01.38547(N) 074 39 49.09626(W) ADJUSTED DF7147* NAVD 88 - 287.201 (meters) 942.26 (feet) ADJUSTED DF7147 ___________________________________________________________________ DF7147 X - 1,276,622.628 (meters) COMP DF7147 Y - -4,654,937.427 (meters) COMP DF7147 Z - 4,155,633.369 (meters) COMP DF7147 LAPLACE CORR- 2.90 (seconds) DEFLEC99 DF7147 ELLIP HEIGHT- 254.50 (meters) (06/06/05) GPS OBS DF7147 GEOID HEIGHT- -32.76 (meters) GEOID03 DF7147 DYNAMIC HT - 287.069 (meters) 941.83 (feet) COMP DF7147 MODELED GRAV- 980,156.9 (mgal) NAVD 88 DF7147 DF7147 HORZ ORDER - B DF7147 VERT ORDER - SECOND CLASS II DF7147 ELLP ORDER - THIRD CLASS I DF7147 DF7147.The horizontal coordinates were established by GPS observations DF7147.and adjusted by the NEW JERSEY GEODETIC SURVEY in June 2005. DF7147 DF7147.The orthometric height was determined by differential leveling DF7147.and adjusted by the National Geodetic Survey in March 2005. DF7147.No vertical observational check was made to the station. DF7147 DF7147.The X, Y, and Z were computed from the position and the ellipsoidal ht. DF7147 DF7147.The Laplace correction was computed from DEFLEC99 derived deflections. DF7147 DF7147.The ellipsoidal height was determined by GPS observations DF7147.and is referenced to NAD 83. DF7147 DF7147.The geoid height was determined by GEOID03. DF7147 DF7147.The dynamic height is computed by dividing the NAVD 88 DF7147.geopotential number by the normal gravity value computed on the DF7147.Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 DF7147.degrees latitude (g = 980.6199 gals.). DF7147 DF7147.The modeled gravity was interpolated from observed gravity values. DF7147 DF7147; North East Units Scale Factor Converg. DF7147;SPC NJ - 231,349.691 136,216.429 MT 0.99990234 -0 06 25.8 DF7147;UTM 18 - 4,529,603.514 528,324.030 MT 0.99960987 +0 13 13.1 DF7147 DF7147! - Elev Factor x Scale Factor = Combined Factor DF7147!SPC NJ - 0.99996008 x 0.99990234 = 0.99986242 DF7147!UTM 18 - 0.99996008 x 0.99960987 = 0.99956997 DF7147 DF7147 SUPERSEDED SURVEY CONTROL DF7147 DF7147 NAVD 88 (06/06/05) 287.20 (m) 942.3 (f) LEVELING 3 DF7147 DF7147.Superseded values are not recommended for survey control. DF7147.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums. DF7147.See file dsdata.txt to determine how the superseded data were derived. DF7147 DF7147_U.S. NATIONAL GRID SPATIAL ADDRESS: 18TWL2832429604(NAD 83) DF7147_MARKER: I = METAL ROD DF7147_SETTING: 59 = STAINLESS STEEL ROD IN SLEEVE (10 FT.+) DF7147_STAMPING: HOPATCONG 2002 DF7147_MARK LOGO: NGS DF7147_PROJECTION: RECESSED 5 CENTIMETERS DF7147_MAGNETIC: I = MARKER IS A STEEL ROD DF7147_STABILITY: A = MOST RELIABLE AND EXPECTED TO HOLD DF7147+STABILITY: POSITION/ELEVATION WELL DF7147_SATELLITE: THE SITE LOCATION WAS REPORTED AS SUITABLE FOR DF7147+SATELLITE: SATELLITE OBSERVATIONS - April 11, 2005 DF7147_ROD/PIPE-DEPTH: 3.7 meters DF7147_SLEEVE-DEPTH : 0.9 meters DF7147 DF7147 HISTORY - Date Condition Report By DF7147 HISTORY - 20020723 MONUMENTED NJGS DF7147 HISTORY - 20050411 GOOD NJGS DF7147 DF7147 STATION DESCRIPTION DF7147 DF7147'DESCRIBED BY NEW JERSEY GEODETIC SURVEY 2002 (RJK) DF7147'THE STATION IS LOCATED IN ROXBURY TOWNSHIP, ON THE GROUNDS OF THE DF7147'HOPATCONG STATE PARK. DF7147' DF7147'TO REACH THE STATION FROM THE US INTERSTATE ROUTE 80 BRIDGE SPANNING DF7147'STATE HIGHWAY 183 AT THE JUNCTION OF INTERSTATE 80, US ROUTE 206 AND DF7147'STATE ROUTE 183, JUST SOUTH OF THE BOROUGH OF NETCONG, GO 0.4 MI DF7147'NORTH DF7147'ON STATE ROUTE 183 TO THE JUNCTION WITH US HIGHWAY 46 AT THE CIRCLE, DF7147'CONTINUE STRAIGHT AHEAD, NORTH ON STATE ROUTE 183 FOR 0.3 MI TO A DF7147'TRAFFIC LIGHT AT THE T-JUNCTION WITH ALLEN STREET, COUNTY ROAD 631, DF7147'TURN RIGHT AND GO 2.3 MI EAST-NORTHEAST ON ALLEN STREET/CENTER STREET DF7147'TO THE JUNCTION WITH LAKESIDE BOULEVARD (COUNTY ROAD 602), PROCEED DF7147'ACROSS LAKESIDE BOULEVARD THEN TO THE LEFT, ON LAKESIDE BOULEVARD FOR DF7147'0.3 MI NORTH TO THE PARK ENTRANCE ON THE RIGHT. TURN RIGHT AND DF7147'GO PASS THE ENTRANCE BUILDING/GATE TO THE LEFT SIDE OF THE PAVILLION DF7147'BUILDING AHEAD AND THE MARK TO THE LEFT, ABOUT 55 M NORTH OF THE DF7147'NORTHWEST CORNER OF THE PAVILLION BUILDING. DF7147' DF7147'THE STATION IS SET NEAR THE NORTH-NORTHWEST CORNER OF THE PARKING LOT DF7147'IN THE GRASS AREA OVERLOOKING THE BEACH AREA. THE STATION IS 0.5 M DF7147'EAST OF THE CURBLINE OF THE PARKING LOT, 1.25 M SOUTH OF A WOODEN DF7147'WELCOME SIGN, 23.0 M SOUTH OF THE CENTER OF THE INLET CURBPIECE AT THE DF7147'ROADWAY LEADING TO THE BOAT RAMP, 7.3 M SOUTH OF THE SOUTH LEG OF A DF7147'PARK BENCH. DF7147' DF7147' DF7147 DF7147 STATION RECOVERY (2005) DF7147 DF7147'RECOVERY NOTE BY NEW JERSEY GEODETIC SURVEY 2005 (SJM) DF7147'RECOVERED AS DESCRIBED. Here, we have a very nice fire hydrant, with 'type not specified. KV3523 I figured that you could resolve these problems.

I went back and looked I still do not see the Z on my end on the original data sheet,I,eye must need glasses. Arhhhhhh HE0206 *********************************************************************** HE0206 DESIGNATION - CV HE0206 PID - HE0206 HE0206 STATE/COUNTY- MO/JASPER HE0206 USGS QUAD - SARCOXIE (1971) HE0206 HE0206 *CURRENT SURVEY CONTROL HE0206 ___________________________________________________________________ HE0206* NAD 83(1986)- 37 04 10. (N) 094 06 56. (W) SCALED HE0206* NAVD 88 - 331.568 (meters) 1087.82 (feet) ADJUSTED HE0206 ___________________________________________________________________ HE0206 GEOID HEIGHT- -29.43 (meters) GEOID99 HE0206 DYNAMIC HT - 331.299 (meters) 1086.94 (feet) COMP HE0206 MODELED GRAV- 979,807.5 (mgal) NAVD 88 HE0206 HE0206 VERT ORDER - FIRST CLASS II HE0206 HE0206.The horizontal coordinates were scaled from a topographic map and have HE0206.an estimated accuracy of +/- 6 seconds. HE0206 HE0206.The orthometric height was determined by differential leveling HE0206.and adjusted by the National Geodetic Survey in June 1991. HE0206 HE0206.The geoid height was determined by GEOID99. HE0206 HE0206.The dynamic height is computed by dividing the NAVD 88 HE0206.geopotential number by the normal gravity value computed on the HE0206.Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 HE0206.degrees latitude (g = 980.6199 gals.). HE0206 HE0206.The modeled gravity was interpolated from observed gravity values. HE0206 HE0206; North East Units Estimated Accuracy HE0206;SPC MO W - 100,250. 884,190. MT (+/- 180 meters Scaled) HE0206 HE0206 SUPERSEDED SURVEY CONTROL HE0206 HE0206 NGVD 29 - 331.476 (m) 1087.52 (f) ADJ UNCH 1 2 HE0206 HE0206.Superseded values are not recommended for survey control. HE0206.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums. HE0206.See file dsdata.txt to determine how the superseded data were derived. HE0206 HE0206_STABILITY: D = MARK OF QUESTIONABLE OR UNKNOWN STABILITY HE0206 HE0206 HISTORY - Date Condition Recov. By HE0206 HISTORY - UNK MONUMENTED USGS HE0206 HISTORY - 1933 GOOD NGS HE0206 HISTORY - 1977 GOOD NGS HE0206 HISTORY - 1977 GOOD NGS HE0206 HE0206 STATION DESCRIPTION HE0206 HE0206''DESCRIBED BY NATIONAL GEODETIC SURVEY 1933 HE0206''AT SARCOXIE. HE0206''AT SARCOXIE, JASPER COUNTY, OPPOSITE THE NORTHEAST CORNER OF HE0206''THE PUBLIC SQUARE, ON THE SOUTHEAST CORNER OF THE BLOCK, AT A HE0206''BRICK BUILDING ONCE OWNED AND OCCUPIED BY THE FIRST NATIONAL HE0206''BANK OF SARCOXIE, AND ON THE UPPER SURFACE OF THE LOWER STONE HE0206''STEP. THE BOTTOM OF A SQUARE HOLE SURROUNDED BY THE LETTERS HE0206''USBM. NOTE-- THE LETTERS U S C AND G SURVEY AND ALTITUDE ABOVE HE0206''GULF OF MEXICO 1088 FEET ARE ALSO CUT IN THE STONE STEP. HE0206 HE0206 STATION RECOVERY (1977) HE0206 HE0206''RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1977 HE0206''RECOVERED IN GOOD CONDITION. HE0206 HE0206 STATION RECOVERY (1977) HE0206 HE0206''RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1977 HE0206''RECOVERED IN GOOD CONDITION. How's this? HE0206_MARKER: Z = SEE DESCRIPTION HE0206_SETTING: 30 = SET IN A LIGHT STRUCTURE HE0206_SP_SET: STEP HE0206_STABILITY: D = MARK OF QUESTIONABLE OR UNKNOWN STABILITY HE0206 HE0206 HISTORY - Date Condition Report By HE0206 HISTORY - 1894 MONUMENTED USGS HE0206 HISTORY - 1933 GOOD NGS HE0206 HISTORY - 1977 GOOD NGS HE0206 HISTORY - 1977 GOOD NGS HE0206 HISTORY - 20030319 GOOD GEOCAC HE0206 HE0206 STATION DESCRIPTION HE0206 HE0206'DESCRIBED BY NATIONAL GEODETIC SURVEY 1933 The top line.... From the NGS datasheet, (from the NGS site) not the GC.com edition. John