New Guy Question/introduction

[omnis_audis]

Hi gang,

I am brand spanking new to all of this. Each summer I am layed off from work. This summer I wanted to do something that gets me out of the house. I purchased a GPS reciever, and decided to start Geocaching. Being on crutches, I thought I would start out searching for benchmarks first, since it seemed some of the GC's were well hidden and hard to get to.

 

So I found a few BM listings near where I live. Today I went out to find my first one.

Based on the picture at http://www.geocaching.com/mark/, I was looking for a 6" or so disk with a lot of writing. I took the info listed from http://www.geocaching.com/mark/details.aspx?PID=DY0388

 

I think I found it, but not sure. Here is why.

 

The discription is a bit outdated. There is no America Blvd. It's now Alamitos (I guess, since I've only lived here for a few years). The location part of the description seems way off too. What I found was a small disk about the size of a silver dollar centered in an 8" square of concrete. It was located on the north curb of Ocean Blvd about 12.5 feet east of Falcon. It was right on the curb, not centered in the lawn as described.

 

The disk it self had very little text on it.

Around the top left it read: C.L.B.

On the top right: B.M. 154

Along the bottom centered: 1998

 

It's location was N 33° 45.913 W 118° 10.414 (+/- 16 feet)

 

I assume the markings mean "City of Long Beach Bench Mark 154" Is the "1998" the year it was installed?? If so, then it's not the one from the listings. Would the city put it's own markers in? So close to a NDS benchmark?

 

The picture I took was with my PDA. It doesn't really show much but a round blob in a cement square. You can't read any text at all. Tomorrow I'll bring my digital camera. I was trying to pack light so I didn't bring it today.

 

Did I find it? Can I officially log it? Or should I resume my search? Or is it not there since there is a posting:

1/1/1964 by NGS (GOOD)

RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1964 RECOVERED IN GOOD CONDITION.

 

Does "Revovery" mean it was taken away? Or just 'observed'?

 

Sorry for such a long post full of newbie questions. I suppose I should have done more research before heading out. I suppose I just wanted to get outside.

 

TIA!

[River_Lime]

Hello, omnis audis, I'm still a newbie myself.

 

I'm still learning everyday about benchmarking, and I have a funny feeling I won't ever learn all there is to know about it. One thing is certain, it is very technical in a number of ways, which personally I find appealing.

 

A recovery is simply a verification that you have located the mark, in its' (as far as you can determine) original location. Any 'Recovery' you log with the NGS comes with a very high standard of accuracy, as this becomes an official document folks rely upon.

 

The description fo DY0388 is as follows:

 

DY0388_U.S. NATIONAL GRID SPATIAL ADDRESS: 11SLT912367(NAD 83)

DY0388_MARKER: DD = SURVEY DISK

DY0388_SETTING: 7 = SET IN TOP OF CONCRETE MONUMENT

DY0388_SP_SET: SET IN TOP OF CONCRETE MONUMENT

DY0388_STAMPING: BM 15

DY0388_STABILITY: C = MAY HOLD, BUT OF TYPE COMMONLY SUBJECT TO

DY0388+STABILITY: SURFACE MOTION

 

You recovered a mark stamped "Around the top left it read: C.L.B. On the top right: B.M. 154 Along the bottom centered: 1998"

 

The "1998" is an obvious indication this is not the correct mark, as it implies the mark was set in the year 1998. Also it should be stamped "BM 15" not "BM 154."

 

Another thing is the coordinates are scaled, which means (somebody can better answer this) the GPS coordinates may be off by quite a bit.

 

I'll let the other more experienced benchmarkers chime in now.

[omnis_audis]

Hi River_Lime,

 

Just as I suspected. Glad I wasn't over zealous and logged a sighting.

 

So then, what did I find? Clearly it's a benchmark of some sort, but not the one listed. While hunting a few blocks away for another (which I didn't find either) on the way home I spied across the street another lil one similiar to the one described. I'm guessing the city installed a bunch.

 

While hunting, I did see a perforated cylinder of green steel with yellow number stickers on it. It stood about 3' tall or so. I've always assumed they were something to do with the natural gas. Could they house the bench mark?

 

The description noted a 'monument', but I saw none. Somehow, I'm starting to think my logic was flawed in thinking benchmarks would be easier to find then geocache's. ;-) I suppose if it was too easy to find, it wouldn't be nearly as much fun.

 

One thing is certain, it is very technical in a number of ways, which personally I find appealing.

 

Yes, I would tend to agree with you. The technical side is very appealing. Is there a primer somewhere on benchmarks? Maybe one that explains the details of the listings?

Thanks

[+Harry Dolphin]

I did a two mile radius search on NGS, and could not find a station labeled 145 C of LB. Many benchmarks are not in th NGS lists, though Long Beach seems to have a lot!

 

DY0388'DESCRIBED BY NATIONAL GEODETIC SURVEY 1954

DY0388'AT LONG BEACH.

DY0388'AT LONG BEACH, 0.9 MILE EAST ALONG OCEAN BOULEVARD FROM THE

DY0388'JUNCTION OF AMERICAN AVENUE, AT THE JUNCTION OF FALCON AVENUE,

DY0388'IN THE LAWN BETWEEN THE SIDEWALK AND THE EAST CURB OF THE AVENUE,

DY0388'26.4 FEET NORTH OF THE NORTH CURB OF THE BOULEVARD, 3.9 FEET

DY0388'WEST OF THE WEST EDGE OF THE SIDEWALK, 3.2 FEET EAST OF THE EAST

DY0388'CURB OF THE AVENUE, 1.5 FEET UNDERGROUND, AND SET IN THE TOP

DY0388'OF A CONCRETE POST, ACCESS TO WHICH IS HAD THROUGH A 5-INCH

DY0388'PIPE WITH A CAST IRON COVER MARKED LBBM.

 

Note that DY0388 is 1.5 feet underground, and accessable through a 5" pipe with a cast iron cover.

The monument referred to is the concete post that the benchmark is set in.

'Recovery' means found and reported to NGS.

The one at the Queen Mary looks interesting? If you don't mind walking around a chain-link fence, and out onto a breakwater.

 

Myself, I find caches easier to find. But a lot of the benchmarks are probably easier for someone on crutches.

[+PFF]

I looked at the area (using the "nearest benchmarks" feature. It certainly is an interesting place for benchmark hunting! The City of Long Beach set a large number of markers, and they are DEEP.

 

You may wish to begin with some easier ones. Print the description for DY0400. While on the datasheet, click on Nearest Benchmarks (in the center of the page). You will see a number of aerial intersection points which can be logged. This will "jump start" your entrance into the hobby and give you practice entering results.

 

Just one word of caution: When you get to the Villa Rivera Tower, you will note that there is a disk at that same geographic location. Don't bother looking for it. It is 17 stories above the street, on a ledge! Even some of the "pro's" won't go out there!

 

-Paul-

[omnis_audis]

Hi PFF,

Ah, I overlooked the below part.

1.5 FEET UNDERGROUND, AND SET IN THE TOP OF A CONCRETE POST, ACCESS TO WHICH IS HAD THROUGH A 5-INCH PIPE WITH A CAST IRON COVER MARKED LBBM.

 

So by that, it is physically 18" below the surface. But wouldn't I find the cast iron cover marked LBBM? Would that be on the surface?

 

And to think, I thought I was lucky having all these BM near by... who knew they were all subterranian!

[holograph]

While hunting, I did see a perforated cylinder of green steel with yellow number stickers on it.  It stood about 3' tall or so.  I've always assumed they were something to do with the natural gas.  Could they house the bench mark?

 

The description noted a 'monument', but I saw none.  Somehow, I'm starting to think my logic was flawed in thinking benchmarks would be easier to find then geocache's. ;-)  I suppose if it was too easy to find, it wouldn't be nearly as much fun.

The green cylinder with yellow stickers is probably something related to a gas, electric, telephone, or cable utility.

 

We should probably start a glossary; maybe one alredy exists? Here's some terminology to start:

 

"station" - this is a general term for the location that was surveyed. I think of it as the place where some surveyor "stationed" himself and his equipment when he took measurements.

 

"intersection station" - usually a highly visible landmark like a water tower or church steeple that has a position that was determined by triangulation, as opposed to having equipment set up on top of it like other stations. The "point observed" is some distinctive feature of the landmark that was sighted on and was the basis of the position calculation.

 

"monument" - a term for some object that is placed to provide a durable record of the survey. Once monuments are put in place, they have legal standing if disputes ever arise. A monument may be a length of steel rebar that has been hammered into the ground, or post that was set, or a pile of rocks (a "cairn") that marked a position, or any number of other things that may have happened to be at hand. A "concrete monument" usually refers to a cylinder of concrete about a foot in diameter that was poured into a hole in the ground with its top flush with or below the surface. If a disk is "set into the top of a concrete monument" it means that such a concrete cylinder was poured, and then the survey disk was set into its top. The whole thing may then be covered over with soil, lying below the surface out of harm's way but available if it ever needs to be used.

 

"control" - an established, measured, and documented reference point for surveys and mapping. Surveyors determine other positions relative to the control points.

 

"horizontal control" - a reference point that is used to establish distance and position (for instance latitude and longitude).

 

"vertical control" - a reference point that is used to establish elevation.

 

"order" - a specification of the accuracy and precision of the measurements that were made. The NGS has standards that must be met for the different orders of accuracy.

 

"bench mark" - among surveyors, this term is used for a specific type of control point that is used strictly for elevation, or vertical control. Among geocachers, the term is used casually to mean any kind of survey marker, either vertical or horizontal control.

 

"NSRS" - the National Spatial Reference System, which is the set of control points that have been measured and recorded to the standards of the National Geodetic Survey (NGS) and which are available to the public.

 

"PID" - a 6-character code that the NGS uses to keep track of control points in their NSRS computer database. This code was invented when the NGS computerized its records. Prior that computerization effort, each control point had a "designation", or name that adequately identified it within its local area, but which may have been duplicated in other parts of the country. The "designation" is a name chosen by the surveyor who establishes the point. The "PID" is chosen by the NGS.

 

"Stamping" - the inscription on the marker. Often this is the same as, or nearly the same as the designation. The PID is never stamped on a disk, since it is only a computer database identifier that is assigned by the NGS after the marker has been put in place, surveyed, and submitted to the NGS for inclusion into the NSRS.

 

"Datasheet" - the document describing the technical details of the control points. The datasheet is provided by the NGS for public use, and it contains details regarding the measured characteristics of the point, as well as description of its condition.

 

"Recovery report" - a portion of the NGS datasheet that describes the condition of the station at times subsequent to its original placement. The recovery reports may contain updated descriptions of how to find the station (the "to reach" description) and may describe its position with respect to nearby objects that are likely to be recognizable (the "ties").

 

"Reference mark" - a nearby disk that was placed in order to help locate the primary station in later years, or to help reset it if if ever becomes damaged or destoyed. Most reference marks are not measured to the standard of the NGS and so do not have their own PIDS. However, some are, and do have their own PIDS.

 

"Azimuth mark" - a station that can be used by a surveyor to establish direction from the primary station. Azimuth marks are points that have lines of sight from the primary station, and which allow the surveyor to align his equipment.

 

"Surface mark" - the marker that is at or near the surface and which is meant to be the primary marker used by surveyors when "occupying" the station, i.e. setting up their equipment to make measurements.

 

"Underground mark" - think of this as an emergency backup system. If the surface mark is ever disturbed or destroyed, the undergound mark may be used to re-establish the surface mark. It is never appropriate for anyone other than a professional surveyor to dig in an attempt to find an underground mark (unless the primary mark itself is slightly below the ground surface). If a datasheet talks of a surface mark and an underground mark, always leave the underground mark alone.

 

"Reset" - a marker that has been put in place as a replacement for a destroyed or disturbed marker. It is usually not in exactly the same location as the original marker, so a reset will often have its own PID and datasheet. If a disk is stamped "reset", but the datasheet makes no mention of being a reset, then the disk does not correspond to the point described by the datasheet and should not be reported as such.

 

"witness post" - an auxiliary marker like a plastic or metal post that has been driven into the ground near the station in order to make it easier to find. A "carsonite" witness post is a plastic post made by one popular manufacturer. Sometimes a witness post will bear a small sign indicating that a survey marker is nearby.

 

"PLSS corner" - a reference mark that was used to establish part of the U.S. Public Land Survey System that is used for property surveys in portions of the South and West of the U.S. The PLSS system consists of townships, ranges, and sections. Before the government transferred or "patented" the land to private owners, it was surveyed and the boundaries of the sections were established with PLSS corners.

 

Whew! This is a smattering of the terms you may encounter. Since surveyors generally are working on some kind of construction project when they set control points, the descriptions can often contain jargon that is related to the type of project that was done. For instance if a mark is set on a bridge, then the description will often contain terms like "abutment", "wing wall", "seat", "balustrade", "deck", "culvert", "headwall", etc., all of which refer to specific parts of a bridge or kinds of bridges. In rural areas, there are also terms that refer to natural settings like "boulders", "outcrops", "ledges", etc. If the markers are long railroad lines, the descriptions may talk of "signals", "crossings", "rails", etc.

 

One of the joys of benchmark hunting is learning some of the trade jargon.

 

edit: an "edit" is a postscript correction to a message Since everyone always wonders what was changed in a message when they see the "edited by" annotation at the bottom, it has become our custom to add a small note like this after making a change. In this case, I added this, and corrected a couple of typos.

Edited June 12, 2005 by holograph

[vagabond]

As I remember American was changed to Long Beach Blvd, also it was American for just a short stretch of downtown lb.

If you have a mapping program measure from Falcon to lb blvd and you'll see it's right at .9ths of a mile.

Also on scaled bms its best to use the directions and not the coords from the gps, I've been as far off as 1/2 mile on scaled marks.

I've been on crutches myself for about a month now, and all I've looked for are benchmarks, all easy ones but not found for awhile, good luck

Edited June 12, 2005 by vagabond

[omnis_audis]

holograph Posted on Jun 12 2005, 07:45 AM

We should probably start a glossary; maybe one alredy exists?

 

Thanks Holograph! Some of them I guessed (and pretty accurate), others were great information. I've saved to my HD to access as needed.

 

vagabond Posted on Jun 12 2005, 08:38 AM

As I remember American was changed to Long Beach Blvd, also it was American for just a short stretch of downtown lb

 

Cool! Good to know. The more I get into this, the more I think benchmark hunting will appeal to my history-buff side... and it's only my 1st week!

 

PFF Posted on Jun 12 2005, 02:47 AM

You may wish to begin with some easier ones. Print the description for DY0400.

 

I was hoping to find a disk. But following PFF's advice, I went for an easier one. Since DY2485 is within walking distance, I went for it. Since there were some posts about bad log's for sightings, I was curious if my log was ok?

 

Tomorrow, I think I'll hit the bluffs. There is one BM and a dozen GC's over a couple blocks. Sure beats daytime TV!

[evenfall]

Hey Jim,

 

Looks like you have a good start on a Benchmark Hunting Glossary for your website there. Nice work! Might be a nice resource for people to refer to.

 

Since we have little in the way of moderation in this forum, I doubt we could pin the thread here. Probably easier to save as a book mark and refer others to the link when needed.

 

Thanks again,

 

Rob

[vagabond]

You may wish to begin with some easier ones. Print the description for DY0400. While on the datasheet, click on Nearest Benchmarks (in the center of the page). You will see a number of aerial intersection points which can be logged. This will "jump start" your entrance into the hobby and give you practice entering results.

 

Just one word of caution: When you get to the Villa Rivera Tower, you will note that there is a disk at that same geographic location. Don't bother looking for it. It is 17 stories above the street, on a ledge! Even some of the "pro's" won't go out there!

 

-Paul-

I think you'll find the old library is gone, so I believe dy0400 will be missing.

I looked at it on usaphotomap (urban color).

I used to live in Long Beach as kid up until 1953, they have really done a lot of improvements in the downtown area I hardly recognize the area anymore.

I imagine a lot of the old marks will be gone but good luck on the ones that are left.