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Along those same lines...I found two today. Actually I just about tripped over both of them as they were right next to a chahe. There is no listing in the database for them and the appear to be the standard USGS markers. Is there a way to report them or am I just wasting my time? I have to assume they put them out there for a reason...

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Along the same lines, sort of:

 

I intend to hunt this one down this weekend.

 

http://www.geocaching.com/mark/details.aspx?PID=KA1097

 

My question is - It appears to me that others have found this "mark" but may have been expecting a standard benchmark disk.  From reading the logs, is the painted square the mark?

 

I didn't know which topic to post this under  :(

 

You will be looking for a chiseled square, on the south wing wall (northeast corner). Just follow the written directions.

 

Good luck! Wish we could come along to find that chiseled square. :(

 

Shirley & John

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2 oldfarts,

Thanks for the help. I decided to put off my "urban" benchmark raid and pursue these instead:

 

http://www.topozone.com/map.asp?lat=39.349...d83&layer=DRG25

 

KA1273 is in the group along the river. I thought this looked like more fun  B)

 

I'll be riding my mountain bike leaving from N39 27.012  W87 22.950

 

Good hunting!

 

Be sure to let us know what you find. :rolleyes:

 

Shirley~

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Rupert2 -

 

There are tons of USGS and other agencies' marks around that are in neither the NGS nor Geocaching databases. (There are a few new ones (2000 - 2004) in the NGS database that are not in Geocaching - yet?). Unfortunately, there is no way (yet?) to logs these in Geocaching and get credit for a "FOUND". I refer to such marks as no-PIDs. Others call them unconsolidated marks.

 

I have found many such marks, and I keep track of them by appending information about them to the datasheet for a nearby mark that has a PID. For am example, see

 

HV2437

 

Will

Edited by seventhings
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Wild T2

 

How did you know that. A local geo/benchmarker noted a find where it appeared that a "local agency" had replaced the USGS disk. Excellent map and if I weren't riding so far I'd tackle the other marks. There's way too many on that map you sent for the time I have, otherwise............. I'll have to put together another trip assuming the others are in the database and I can acquire the information needed.

 

Thanks, I'm really psyched to get down there now.

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2oldfarts,

Well after spending 5 hours and 10 minutes on the bike today, here are the numbers.

My route included 21 benchmarks. I was only able to search for 5. Of those I only found 1. I did have an interesting time however. In addition to the one that I did find, I found these as well:

TT 18D USC&GS 1938

KA1275 as replaced by Indiana DNR

Vigo 13 as placed by State Highway Commission of Indiana

 

It's interesting that in the case of TT18D no mention is made in the database however TT19D which is a few miles West was set in 1947. TT18D is stamped 1938.

 

DNR of Indiana placed a series of benchmarks in the area around KA1275 and it appears even replaced KA1275.

 

SHC of Indiana Vigo 13 I just happened to spot out of the corner of my eye crossing a bridge over a drainage ditch less than a mile from my house. Not bad after 5 hours of riding:)

TT18D

SHC IND Vigo 13

KA1275 DNR IND

Edited by mrh - terre haute
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I work as a surveyor for DNR so I am familiar with our old project in the area. It was a feasibility study with the Army Corps of Engineers to study the potential for new levees to protect the cropland from flooding, and do some environmental restoration as well.

 

We recovered the NGS control, set some new control of our own, did aerial photography for mapping, and did some other on-the-ground surveying.

 

We gave our data to the engineers at the Corps for preliminary review and study. As it turned out, the benefit cost ratio was just a little better than 1 to 1 and the project was dropped.

 

Hopefully our control will still be there when someone in the future decides to re-study the area.

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Wild T2

I've made 2 trips into the Greenfield Bayou and so far this is what I've found:

DNR VIGO 13

http://www.mach500.net/homes/users/mikehannum/ka1275dnr.jpg

DNR VIGO 17

http://www.mach500.net/homes/users/mikehannum/dnrvigo17.jpg

DNR VIGO 27

http://www.mach500.net/homes/users/mikehannum/dnrvigo27.jpg

DNR VIGO 29

http://www.mach500.net/homes/users/mikehannum/dnrvigo29.jpg

DNR VIGO 30

http://www.mach500.net/homes/users/mikehannum/dnrvigo30.jpg

DNR VIGO 31

http://www.mach500.net/homes/users/mikehannum/dnrvigo31.jpg

DNR VIGO BAYOU1

http://www.mach500.net/homes/users/mikehan...rvigobayou1.jpg

 

That's about as well as I can do with no data sheets. I plan to make one more trip down as I have not looked for the marks in the Northern section of the Bayou along the levy.

 

This photo is the opposite end of the bridge from DNR VIGO30. There is another topic in the Forum for a benchmark photo contest. Since this isn't an NGS benchmark technically it can't be entered so I'll just put it here:

 

bridge.jpg

Edited by mrh - terre haute
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mrh,

 

446 ft is the elevation which was stamped on the disc, however the Topo seems to show EL=447 and you somehow got your consumer grade GPS to give you EL=446, which was a very good day for consumer grade GPS derived elevation... It could be a typo... I would tend to trust the leveled stamping myself, at least from the armchair. That would be USGS TT 12D 1938 In Indiana, I assume. DaveD may be able to research the original leveling for this station.

 

So, N39 19.044 W087 33.225 Elevation 446 feet (your GPS derived elevation) shows a Datum shift of (NAVD 88 minus NGVD 29): -0.111 meter or 4.37 inches less, for those coordinates. So the 446 (NGVD 29 based on the original date of the leveling) is now a little more than 4 and 1/3rd inches lower than it was due to datum shift to NAVD 88 or 445.63 FT. That bench was placed and stamped during NGVD 29 Datum times due to the elevation stamping, which is a convention that stopped in the 60's, and they stamped the year on it besides.

 

What ever the disc was stamped as, if accurate (since the topo does not seem to agree), is now 4.37 inches lower than the stamped elevation for latest, Datum shift adjusted, orthometric height. Just remember, that datum shift only applies to that set of coordinates. Geoid heights differ everywhere and the datum shift is geoid derived.

 

As an aside, and FYI to all, this thread took me 6 minutes and 25 seconds to load due to the file sizes of the photos. Your milage may vary. I love the photos as much as anyone but can we try to limit the file sizes to around 100k each? If they cannot be resized, is it feasible to link to the photos somewhere off site so they will open in a new window? That is so much faster. When a thread gets this long, although there is no reason why a thread cannot be any length, or as long as is needed, all the photos just kill the load up... My hope is we can speed them up a bit somehow is all. Thanks! :-)

 

Rob

Edited by evenfall
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As an aside, and FYI to all, this thread took me 6 minutes and 25 seconds to load due to the file sizes of the photos. Your milage may vary. I love the photos as much as anyone but can we try to limit the file sizes to around 100k each? If they cannot be resized, is it feasible to link to the photos somewhere off site so they will open in a new window? That is so much faster.  When a thread gets this long, although there is no reason why a thread cannot be any length, or as long as is needed, all the photos just kill the load up... My hope is we can speed them up a bit somehow is all.

Gee, Rob, just because pictures are 800x602 pixels? I noticed it was not a GC site picture. They came from http://www.mach500.net (Don't click on this, it takes forever to load!) web site. GC automatically limits pictures to less than 100K but has no control over other web sites. :grin:

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Rob and C-papa

 

Thanks for all the great info. I forget not everybody is on broadband (900K DSL here).

I actually run the same re-sizing macro on stuff I upload to my website that I do when I send photos up to the Geocaching / Benchmark galleries. It's no problem to check them out though to make sure they are more easily attained by all you guys 'cause I really do need the feedback, + and -. I'll get them resized ASAP!

 

Mike

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All images are resized and / or linked as opposed to displayed ( I couldn't edit all my posts).

 

I should mention that the coords. are WGS84 if that matters. Also, I had made two previous attempts at locating TT 12D with no luck. This particular trip I decided to stop one more time because I saw the tell-tale hole in the middle of the road indicating the possible presence of a survey crew. I made a swipe with the metal detector with no joy. Then I noticed a slight depression alongside the road some 20 feet beyond my previous search area. Passed the detector over it and sure enough there was something down there.Started digging and three inches below the surface was the disk.

 

mrh

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Hi Mike,

 

You mentioned, I should mention that the coords. are WGS84 if that matters.

 

In fact, it does matter, and a lot more than you might think, especially if you want to position yourself accurately, and utilize the accuracy that these survey markers represent. First let's define the Datum.

 

A datum, basically put, is a reference system for measuring, which is based on a specific set of measurements.

 

How this matters is this; The survey markers used by geocaching are owned and placed by National Geodetic Survey. They created and maintain the Data for these markers and these markers represent the NSRS, the National Spatial Reference System. The NSRS is the basis, in part, for the NAD 83 Datum. They were also the basis, in part, for the NAD 27 Datum. The differences between the two Datum is the mathematics and methodology behind the observations and calculations. So, You see, these markers are the physical items that represent NAD 83 in the world.

 

Not to confuse this, yet it is very important to note, If the survey marker was not included in the NSRS, then NGS did not adjust, or calculate its value for NAD 83, or in the case of the Vertical Elevation NAVD 88, which superseded NGVD 29. In the case of a lot of the old USGS Bench Marks, which are printed on USGS Maps, If we do not find them in the NSRS, which is the NGS Database, then if they were monumented prior to 1986, (the year NAD 83 was rolled out) it is likely the working Datum for that marker is NAD 27, However, if you are using an updated USGS Mapping product, and the Datum on that map is NAD 83, then the location of the BM on the map has been at the very least, Cartographically corrected. You would need to write to the USGS for more information than that.

 

Now in the case of the VIGO stations, the DNR could have submitted their Data to the NGS for inclusion in the NSRS if they had chose to. If the data met the standards, the NGS could have included it. All 50 states have an interest in survey at the Geodesy level and will submit many of their newly monumented stations to the NGS for inclusion in the NSRS. elcamano could probably share a few stories about that in his career at Michigan DOT.

 

I wrote up definitions for the 3 major horizontal Datum in use in the US today. At the highest levels of accuracy they do not interchange. To Quote Kenewah's signature; "New tools are no replacement for old rules". For the most part, it really is a good idea to observe the Datum being used by the system or map, the reason for this is because each Datum is derived in it's own unique way, and there can be quite a shift between them if you try to use them interchangeably. NAD 27's Datum shift can be large and widely variable based on the location it is taken, when compared to NAD 83 and WGS 84. Between WGS 84 and NAD 83 the Shift is also variable but within one (1) meter taken both vertically and horizontally.

 

Ok, the definitions:

 

NAD 27

 

NAD 27 stands for North American Datum 1927. Originally developed by the agency now known as the National Geodetic Survey, an agency overseen by the U.S. Department of Commerce. Based horizonally on a single fundamental point known as Meade's Ranch, located in Kansas, it was primarily derived through theoretical, mathematical models of the earth's shape and highly precise land surveying of the United States. The Vertical Component for use with NAD 27 was known as NGVD 29, (The National Geodetic Vertical Datum of 1929) since superseded, a Datum fixed to a series of Tidal references in the United States and Canada which was for use when precisely measuring vertical elevations.NAD 27 was the precursor to the NAD 83 Datum which is Satellite based and still being perfected through improved observed mathematical models and real time national monitoring to this day. For the highest accuracy, Datums should NOT be used interchangeably. Always remember to set your GPS to match the Datum that the map you are using is based on, Whether that is NAD 27, NAD 83, or WGS 84.

 

NAD 83

 

NAD 83 stands for North American Datum 1983. Developed by the National Geodetic Survey, an agency overseen by the U.S. Department of Commerce. This is an earth centered, 3 dimensional Datum, but is highly accurized horizontally, and is primarily for use in the United States and North America. It is derived from highly accurate, continually improved mathematical models of the earth, highly precise land surveying, sattelite observations, and a large network of real time national ground station monitoring to this day. The Vertical Component for use with NAD 83 is known as NAVD 88, (The North American Vertical Datum of 1988) a Datum which is fixed to one Bench Mark located in Quebec Canada, for use when precisely measuring vertical elevations. Depending on the order of accuracy, the accuracy of these Datum generally ranges from 1 millimeter to 5 centimeters. For the highest accuracy, Datums should NOT be used interchangeably. Always remember to set your GPS to match the Datum that the map you are using is based on, Whether that is NAD 27, NAD 83, or WGS 84.

 

WGS 84

 

WGS 84 is a Department of Defense (DOD) owned Datum, developed primarily for worldwide U.S. Military use, yet has many world wide users. It's precursors were WGS 72 and WGS 66. It is an earth centered 3 dimensional Datum which handles Horizontal and Vertical all-at-once, is Satellite based and is the basic convention for use with GPS. Very little physical infrastructure is included, yet it is still being perfected and adapted for accurization through the National Geospatial-Intelligence Agency. It is further improved, and observed with third party mathematical models, and localized, realtime worldwide monitoring by various U.S. agencies and world wide countries to this day. It is derived and monitored in a similar manner to that of NAD 83, but uses different Mathematical models and earth station monitoring. Accuracy is high, however, it varies based on where in the world you are. It is Important to note however, that though NAD 83 and WGS 84 are both based from the same Satellite Constellation, they used different mathematical models and are NOT the same Datum. For the highest accuracy, they should NOT be used interchangeably. Always remember to set your GPS to match the Datum that the map you are using is based on, Whether that is NAD 27, NAD 83, or WGS 84.

 

The bottom line is that the WGS 84 Datum has little to do with these particular survey markers at all. The only ones I know of that would, would have been placed by the USAF's geodetic Squadron, which was taken over by the Defense Mapping Agency, now doing business as, yet skipping over a name change or two, the National Geospatial-Intelligence Agency or NGA, they are overseen by the DOD. The Survey Markers they set are pretty rare, and the data for them is not available.

 

This is only part of the big picture, and it is a pretty big picture. I hope that helps explain it.

 

Rob

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