Eastern Oblique Arc - Western and Southern Extension of Kent Island Base Line

[+Ernmark]

I was going to post a reply to Papa-Bear-NYC's EOA thread on the Epping Base Line , but thought it would be better to have a separate thread broken into the parts listed on Holograph's wiki. Papa-Bear had stated the desire to keep track of EOA recoveries, so I will add mine:

 

Unfortunately this won't be a very exciting story as there was no mountain to climb or serious measuring - however, it was nice to get a chance to look for one of these stations. The 'Mizziz' wanted to go on a shopping junket in the Baltimore-Washington area & I found myself about 5 miles from WEBB (JV5810)...so I charted a course to hunt for BMs toward that direction.

 

After warming up with a few benchmarks along the way, I found the most difficult part of the search was getting access to the area. Fortunately, the station is located on county government property & there were a few workers on-site at the property who explained the best way to get there – I would not have searched otherwise as the property is posted.

 

I had hoped to be able to find the original referenced stone markers placed 5 feet (more or less) to the E, N, & , S of the main station, but they were not visible – due apparently to a mound placed around the monument, most likely in 1933, when familiar USC&GS bronze disk were set. Per the (2nd) 1933 recovery – “SUBSURFACE MARK A CONE BURIED 1.7 FEET BELOW THE SURFACE WAS RECOVERED AND A TRIANGULATION MARK CEMENTED INTO THIS CONE BY MEANS OF A PLUMBING BENCH AND A SURFACE MARK WAS ALSO SET BEING SEPARATED FROM THE SUBSURFACE MARK AND PLUMBED OVER THE SUBSURFACE MARK” By 1942 the original reference posts were not found.

 

surface mark (close up was too blurry to use - I was either too excited or didn't have enough light)

 

setting showing mound which probably covers reference stones

 

Although this was not a 'hard find', it was interesting interpreting the old references to plot the location of the station in relation to the old driveway (houses are long gone) and what appears to be an old yard fence.

 

I also found an interesting stone (actually the first thing I found when arriving at the site) which appears to have been used at least - at some point - for surveying purposes...it looks like there was a cross chiseled on the top..although it isn't referenced in the datasheet.

 

?

 

well...maybe not the most exciting old recovery (even for me)...but it was still more fun than pouting in a shopping mall!

 

- E

Edited February 16, 2009 by Ernmark

[Papa-Bear-NYC]

Good work Ernmark! It's great to see some interest in this historic survey south of my usual stomping grounds.

 

One must assume the original cone is still under the surface mark (with a disk cemented in it's top). Pretty impressive. I've noticed the old cones are almost all gone. We're lucky in New England where many marks are mounted in bedrock so there's a fighting chance of finding the original.

 

I've updated my map - here's the link for that section: Kent Island Base Net Gmap

 

If you click on "WEBB" you should get your recovery date, a bunch of links and even a thumbnail which links back to the photo in your GC log.

 

Edit: I just clicked on the NGS link on the map and I see WEBB is now a GPS station. It's so cool to see a station established in 1850 get remeasured by space age technology to an accuracy of centimeters!

Edited February 16, 2009 by Papa-Bear-NYC

[+Klemmer]

Papa Bear:

How "close" were they in 1850 to the current GPS position? Or is that too difficult to answer with all the different "datums" in the years between?

[Papa-Bear-NYC]

Papa Bear:

How "close" were they in 1850 to the current GPS position? Or is that too difficult to answer with all the different "datums" in the years between?

Datums changed probably 3 times (1900, 1927, 1983), but here's the current and superseded positions from the datasheet, which goes back to NAD 27:

JV5810* NAD 83(2007)-  39 05 26.60260(N)	076 40 29.19795(W)	 ADJUSTED  
JV5810  ------- Accuracy Estimates (at 95% Confidence Level in cm) --------
JV5810  Type	PID	Designation					  North   East  Ellip
JV5810  -------------------------------------------------------------------
JV5810  NETWORK JV5810 WEBB							 13.82   8.43  27.99
JV5810  -------------------------------------------------------------------
JV5810
JV5810						  SUPERSEDED SURVEY CONTROL
JV5810
JV5810  ELLIP H (09/18/02)   39.553  (m)					   GP(	   ) 4 2
JV5810  NAD 83(1991)-  39 05 26.60330(N)	076 40 29.19832(W) AD(	   ) 1
JV5810  NAD 83(1986)-  39 05 26.60045(N)	076 40 29.20867(W) AD(	   ) 1
JV5810  NAD 27	  -  39 05 26.20930(N)	076 40 30.32650(W) AD(	   ) 1

So the big jump was between NAD 27 and NAD 83. I think they used the original angles whenever they did a readjustment, so the changes are mostly in the 3rd decimal place in the seconds in each of the 3 NAD 83 adjustments.

 

DaveD or NGS Surveyor might know if the original angles measured in 1850 were still used until GPS came along.

 

Dave? George? Are you there?

Edited February 16, 2009 by Papa-Bear-NYC

[+Ernmark]

Papa Bear - thanks for the link - I'd forgotton about your maps...I'll get to work on more sites down there as the shopping trips allow

 

I'd also like to get to MARYLAND HEIGHTS S (JV4626)- BDT, want to meet up & give it another shot? (from the looks of the terrain, there should be at least a half dozen of us searching!)

 

Klemmer & TeddyBearMama - This dosen't have a whole lot of relevance to your question posed above, but but I was pleased to see the Google Earth registration was about spot-on!

Edited February 16, 2009 by Ernmark

[Papa-Bear-NYC]

Papa Bear - thanks for the link - I'd forgotton about your maps...I'll get to work on more sites down there as the shopping trips allow

 

I'd also like to get to MARYLAND HEIGHTS S (JV4626)- BDT, want to meet up & give it another shot? (from the looks of the terrain, there should be at least a half dozen of us searching!)

 

Klemmer & TeddyBearMama - This dosen't have a whole lot of relevance to your question posed above, but but I was pleased to see the Google Earth registration was about spot-on!

I'm glad you pushing on. I separated the parts south and west of the Kent Base Net into a separate section. Here's the map: Western and Southern Extensions of Kent Island Base Net Gmap

 

It shows only BDT's 2004 DNF of Maryland Heights. Definitely one that would attract my attention if it were not so far out of my commute.

 

Peach Grove (HV4830) over in Arlington is another one. Maybe you could get access to that fenced in area. It's apparently near a radio tower but the aerial view shows it's not under a building or anything. Click on Peach Grove then click the Map link. Here it is (I'll save you a few clicks): Peach Grove GMap. Sure ain't no Peach Grove there now!

Edited February 17, 2009 by Papa-Bear-NYC

[ArtMan]

Count me in on any group effort to recover MARYLAND HEIGHTS S, but I wouldn't be adverse to waiting until it gets a bit warmer. Incidentally, the Google Maps satellite image captured an aircraft flying over area. I've never seen that before.

 

Also, for the record, PEACH GROVE RESET (HV4830) is not in Arlington, but is in the nearby area known as Tyson's Corner.

 

-ArtMan-

Papa Bear - thanks for the link - I'd forgotton about your maps...I'll get to work on more sites down there as the shopping trips allow

 

I'd also like to get to MARYLAND HEIGHTS S (JV4626)- BDT, want to meet up & give it another shot? (from the looks of the terrain, there should be at least a half dozen of us searching!)

 

Klemmer & TeddyBearMama - This dosen't have a whole lot of relevance to your question posed above, but but I was pleased to see the Google Earth registration was about spot-on!

I'm glad you pushing on. I separated the parts south and west of the Kent Base Net into a separate section. Here's the map: Western and Southern Extensions of Kent Island Base Net Gmap

 

It shows only BDT's 2004 DNF of Maryland Heights. Definitely one that would attract my attention if it were not so far out of my commute.

 

Peach Grove (HV4830) over in Arlington is another one. Maybe you could get access to that fenced in area. It's apparently near a radio tower but the aerial view shows it's not under a building or anything. Click on Peach Grove then click the Map link. Here it is (I'll save you a few clicks): Peach Grove GMap. Sure ain't no Peach Grove there now!

[+Ernmark]

Count me in on any group effort to recover MARYLAND HEIGHTS S, but I wouldn't be adverse to waiting until it gets a bit warmer.

My favorite time to ascend the mountains is Late March or Early April - warmer, but before the leaves/ticks/poison ivy are in full force & you can still get a decent satellite lock.

 

...maybe we could even cajole PFF to cross the Potomac for this one!

[Papa-Bear-NYC]

I got to thinking about the documentation date for Webb. The datasheet says 1896 but in the dataset form my maps I have 1850. I usually get those from the Special publication for the EOA, when I suspect the datasheet has a later date (as in this case - since this whole section was surveyed in the 1850s and 1860s).

 

So I looked it up and found this

 

 

This gives three sets of observations: 1848, 1850 and 1868. Then I found a note a little later in the publication that said the station descriptions were in Special Publication No. 4 (1900) which was for the Transcontinmental Triangulation. It seems this base net was used in both surveys. So I downloaded that (19 Mb) and found this:

 

 

My, my: this says the station was established in 1846! That sound a lot better than 1896, don't you think?

 

I'll change the data for my map. I love it when a little searching makes a recovery even better, don't you!

 

Maybe some of you Maryland guys can look up and see what you can find for Maryland Heights. Maybe you can improve on the 1865 date given in the data sheet.

Edited February 18, 2009 by Papa-Bear-NYC

[+Ernmark]

Awesome!

 

I had also considered looking for Soper &/or Stabler instead, but took a guess that Webb had the best chance of being intact & I only had a few hours to hunt that day - I'm glad I chose to look for Webb.

[+Klemmer]

And:

Have you noticed that the person setting the mark was A.D. Bache. ??

He was one of the early pioneers of the Coast Survey (second director, appointed in 1843), and the great-grandson of Benjamin Franklin. The link above is to a quite lengthy profile, and I confess I only scanned it for the Survey references. Here is bit more concise history of his work. Really interesting mark(s). Wish I was closer (well, sometimes.....).

Edited February 18, 2009 by Klemmer & TeddyBearMama

[+Ernmark]

Regarding the potential MARYLAND HEIGHTS S revisit - both ArtMan & mloser had expressed interest in possibly joining forces to ascend to the summit (sounds like something from Pixar), but I haven't heard back from either of you yet - how's May looking? (here in Southern PA the mountain tops above 1000' are still relatively devoid of leaves) I'm also wondering if anybody has run across any notes on the referenced unpublished station PIVOT - JV4627? Looks like a nice 1000' vertical elevation change hike..but at least it's not all at once!

[Difficult Run]

Regarding the potential MARYLAND HEIGHTS S revisit... I'm also wondering if anybody has run across any notes on the referenced unpublished station PIVOT - JV4627? Looks like a nice 1000' vertical elevation change hike..but at least it's not all at once!

I'm not really sure that MARYLAND HEIGHTS S is the older station. I suspect that MARYLAND HEIGHTS RESET is older, but I can't prove it.

Also, I've wondered what the "S" suffix stands for? - South or Sullivan? Wouldn't it be grand to see the original field notes?

 

Regarding PIVOT 1865, it references a pivot gun which stood at that location during the Civil War. (probably a drill hole set close by).

Maybe, I can dig up an old map of that period which remember seeing in a book a few years ago.

 

While I'm on the subject of the EOA, there are several stations which I believe were part of the original survey:

SUGAR LOAF 1865 S - (South or Sullivan?)

HIGH KNOB 1865 (in MD) - Unpublished datasheet of the original mark is CA2598

WATERY MT 1871

ELLIOTTS KNOB RESET 1878

HIGH KNOB 1865/1884 (in VA)

PARIS RESET - (1927 note: "STATION WAS MARKED BY A CIRCULAR PILE OF ROCKS, AND IS PROBABLY THE INTERSECTION STATION PARIS, OF THE EASTERN OBLIQUE ARC.")

 

PapaBear - Can you check your sources to see if any of the above stations "fit" into the EOA?

I've tried to dig through Special Publication #7, but I get lost real easy!

 

On a side note:

Access to PEACH GROVE RESET would most likely be inaccessible to the geocaching community.

 

Sorry if I've rambled....

~ Mitch ~

[Papa-Bear-NYC]

...

 

While I'm on the subject of the EOA, there are several stations which I believe were part of the original survey:

SUGAR LOAF 1865 S - (South or Sullivan?)

HIGH KNOB 1865 (in MD) - Unpublished datasheet of the original mark is CA2598

WATERY MT 1871

ELLIOTTS KNOB RESET 1878

HIGH KNOB 1865/1884 (in VA)

PARIS RESET - (1927 note: "STATION WAS MARKED BY A CIRCULAR PILE OF ROCKS, AND IS PROBABLY THE INTERSECTION STATION PARIS, OF THE EASTERN OBLIQUE ARC.")

 

PapaBear - Can you check your sources to see if any of the above stations "fit" into the EOA?

I've tried to dig through Special Publication #7, but I get lost real easy!

 

...

 

Sorry if I've rambled....

~ Mitch ~

A good condensation of the whole thing is given by Holograph's site: EOA site

 

I also have created a Google map which is complete down to So. Carolina. Click on a section to get a closer virew showing the stations: EOA Map

 

I'm going out so I can't check your list right now, but I'll try to get to it later.

[+Ernmark]

..regarding PIVOT - at least I will be able to project some decent coordinates from the MARYLAND HEIGHT S datasheet

[+Ernmark]

Greetings! EOA season is coming up again & I was still wondering if anybody has run across any notes on MARYLAND HEIGHTS S or the nearby referenced unpublished station PIVOT - JV4627 ?

[Papa-Bear-NYC]

..regarding PIVOT - at least I will be able to project some decent coordinates from the MARYLAND HEIGHT S datasheet

Something that I mentiond in another thread a while back, is that they now give complete adjusted coordinates in the PID list even for unpublished stations.

 

If you go to the Datasheet PIDs Form (that's a link) and put in JV4627 in the little box and hit submit, you get this:

 

|Dist|PID...|H V|Vert_Source|Latitude.....|Longitude.....|Stab|Designation
|----|------|- -|-----------|-------------|--------------|----|-----------
|....|JV4627|2 .|29/SCALED..|N392002.90157|W0774309.31645|....|PIVOT

 

Notice the Latitude and Longitude fields. The are now given as DDMMSS.sssss. That is as accurate as you get on the data sheet.

 

When I asked about it, someone from the NGS (Dave? George?) said they recently started doing that since certain GIS systems use the PID lists to generate maps.

 

Use it - Go find it! (sorry, can't join you).

[+Ernmark]

Thanks ! The team is beginning the planning stages!

[+Ashallond]

Good luck! I can't wait to read the story of the travels.

[+Ernmark]

Following is an update on the MARYLAND HEIGHTS S (JV4626) project:

 

Ominously, the date selected for the 4 1/2 mile round trip, 900+ elevation change quest was April 1st. The team consisted of myself & mloser (ArtMan was on assignment). We planned to search for this mark as well as the elusive non-published PIVOT (JV4627).

 

Having stocked up on supplies (water, soda, peanut butter/bologna sandwich, peanut M&Ms, camping fork, measuting tape, camera, wi-fi enabled benchmarking phone we began the ascent. At one point (although I missed it) it was marked that President Lincoln was being taken on a tour up this trail to an over look & having looked up at the trail from that spot said something to the effect of 'that's far enough'.

 

Passing several remains of gun emplacements, etc., we continued beyond the more traveled trail to the overlook and headed farther up the mountain - stopping occasionally for quick brakes earned by middle-aged benchmark hunters. The trail lead us first to the projected coordinates of the unpublished PIVOT. After a few minutes we found the closest thing we could vind to a 19th Century station:

The problem with this (barring whether this is actually what we were looking for) is that it is oddly-triangularly shaped & it is too close to an an edge for both of us to feel confident that this is a man-made drill hole:

 

After a good 45 minutes or so, we proceeded N for 221 meters to search for our main target - MARYLAND HEIGHTS S. Mloser will have to confirm, but my guess is that we spent at least an hour scraping rocks, overturning & inspecting stones for any sort of markings. Due to the fact that vegetation was still dormant at 1381 feet & had a decent satellite signal, we were able to keep our search area to a roughly 30' oval resembling a loaf of Italian bread oriented just to the E of the trail. Our only clue to this was that it was a drill hole in a boulder - however, every logical exposed boulder had no drill hole. We excavated as much as was logically possible, given being on park grounds, and with a curious visitor or 2 happening by every 20 minutes or so. We spent at least an hour scraping, looking, moving, thinking, before finally coming to the conclusion that without completely scraping a entire 30'x15' section of the trail & E shoulder, this will remain unfound.

Perhaps a professional-grade GPSr and good constellation could reduce the search area - although 3 HH2 GPSr units gave us similar results..hopefully we were close.

 

We had one more place to go while up there - MARYLAND HEIGHTS RESET

Here we were able to locate the station and all three Reference Marks quickly. We attempted to locate the five chiseled reference marks from 1871, but were unsuccessful - we did locate the cross found by BDT in 2004.

 

After milling around the fort for a few minutes, we began the return trip - stopping again at MARYLAND HEIGHTS S ..just in case. After returning to Harpers Ferry (with 15 minutes to spare to catch the last shuttle to the parking area), we opted to head E to look for a few marks along an abandoned RR line until dark...with much greater success.

 

Not every find results in success, but you're never sure what's up there until tou check it out yourself

 

The search to complete the E.O.A. continues...

Edited April 3, 2010 by Ernmark

[foxtrot_xray]

Great! Sorry I missed it. Next time you guys get down this way, let me know. I think I can manage a 4.5 mile hike. If not, the ex-cer-size will do me good anyhow.

[Difficult Run]

Given that this is National Park property as well as a Civil War site, I have serious concerns about 'scraping rocks' and 'overturning stones' to find a geodetic mark.

I'd hate to see the NPS perceive benchmark hunters as disturbing cultural or natural resources.

 

That being said, here's an 1863 map of Harper's Ferry showing the location of the Stone Fort and nearby gun emplacements:

 

 

Taken from "The Official Military Atlas of the Civil War". Plate 42-1.

Apologies for the low resolution scan. I'd be happy to email a better resolution image to anyone that asks.

 

~ Mitch ~

[+Ernmark]

I'd hate to see the NPS perceive benchmark hunters as disturbing cultural or natural resources.

..just to allay any concerns, we did no wholesale excavations or 'tossing' of stones (PIVOT shot was the most intense 'excavation' which encompassed pulling back a small layer of accumulated 'recent' debris) - that's why this one will probably remain unfound. With another good mark 200 meters to the N, if anyone would want to do any surveying, 'RESET' would do just fine.

 

PS - we actually thought about contacting you to join us as if I remember correctly, you've had some good luck w/ marks along the Potomac

Edited April 4, 2010 by Ernmark

[Difficult Run]

Thanks for the offer. It would have been a fun time getting together with the both of you.

... and yes, I've had some very good success with finding a number of marks in the heavily wooded sections along both shores of the Potomac.

I have to thank Artman, Seventhings and BDT for leaving the really difficult or obscure monuments unfound in the immediate area.

It has forced me to carefully examine and research any info I can gather before I even attempt a recovery. - Thanks guys!

 

Back on topic:

I'm certain that MARYLAND HEIGHTS S and PIVOT are lead filled drill holes as was customary at the time.

So the use of a metal detector, (with the cooperation and blessings of the NPS), could produce a recovery of both marks.

 

I know some of you might find the idea of the NPS allowing metal detectors in finding a mark unlikely or even impossible given their blanket ban on the use of same,

but I have obtained permission to do so and the rangers even offered to bring the detectors! (As of yet, I haven't taken them up on the kind offer.)

 

By the way, did you use the coordinates given by the NGS or projected coords using the callouts from the boxscore?

 

~ Mitch ~

[+jwahl]

I have to think that there is a considerable possibility that the hole you show is it. Remember that it was probably drilled by hand and may have suffered a bit of erosion over the years.

 

In New England you see drill holes as monuments a lot, but they are more machine drilled.

 

That being said, I would love to be able to help by getting survey grade position on it at some point. There are problems with that though:

 

1) The station is listed as second order which to my intuition in this situation and with the apparent longevity of the observations, means probably within a few feet. I need to look at a modern datasheet to see if it is quantified by NGS.

 

2) Reliable results with finite occupation times are working against rapidly increasing canopy (leaf out) of hardwoods. So for a GPS session worked against a nearby station an hour might do it. If you had to work against CORS stations perhaps 4 or more hours.

 

3) My situation in regards to family health issues does not provide me with much of a chance to get away from home.

 

A good mystery is fun to solve. Almost easier would be a traverse from a good station to this area. However given the weight and quantity of equipment for 1 or 2 people to handle GPS seems like a good thing to try.

 

There is still a mystery at sugarloaf to explore.

 

Not to mention a few other very old stations in the EOA that are very close to me, but under threat of eminent destruction.

 

Maybe some of you with more energy and time can help me with that in return for some help at Maryland Heights?

 

- jlw

Edited April 6, 2010 by jwahl

[mloser]

Despite still being tired and sunburned from last Thursday's trip, I would be happy to return with a battalion of benchmark hunters and re-look for the missing points, especially if we could get some better tools.

 

I was truly disappointed that we found nothing resembling a "boulder" at the Maryland Heights S location--Ernmark and I looked carefully at every likely "boulder" but most turned out to be what we considered "rocks", and loose ones at that. The most stable boulders were completely without holes. I would say we searched a 100 foot corridor along the trail, about 20-30 feet in width, concentrating on the center 30-40 feet.

 

I doubt that the hole is lead filled. I believe I found Sugar Loaf S (as did BDT) and it was just a big ol' hole. Since it was also set by JA Sullivan I am willing to bet that Maryland Heights S is similar.

 

As for Pivot, that hole sure looked man-made but it was in such an unlikely spot we doubted our find (not that it was much of a find. It is quite obvious.) It is also very close to the edge of the cliff and would have been hard to occupy. Then there is the fact that it is at the edge of a break in the rock. Granted, that break may have happened later. There were no markings around the hole either--no triangle or chiseled letters.

 

Maryland Heights Reset was a disappointment also. Ernmark found the missing RM disk, which was cool, but we couldn't find any of the original chiseled reference marks. We measured distances and angles and usually ended up where there was no rock to carve anything on. We even tried reverse azimuth directions and failed.

 

So if anyone wants to go back I am game!

[+jwahl]

I think there are these situations where maybe it goes beyond 'normal' benchmarking' etiquette, but where surveying may be applied. And the altruistic goal in the end is to find and document historic, if not otherwise important, points. Surveyors also have a natural historical bone or two in their make up and even historians and archeologists can claim some rights to the use of technology to 'find things'.

 

So here are some of the skills I can offer for some of these important missions 'insert mission impossible theme'...

 

I have transits, compass' and at least one theodolite and know how to use them. I can (if the skies are willing) obtain astronomic azimuth by solar or polaris observations that might help mapping some of these mystery areas. That is obtaining geodetically relatable direction that can be used to tie together objects in close proximaty. When woods are involved as they often are in the east, this usually means some traversing.

 

In addition I have tools to measure distance, but nothing that special, i.e. the EDM's I have date back 25 years and weigh a bit, but I also have a number of survey tapes. Taping requires some skill and more than one person usually.

 

And lastly I have some single frequency GPS equipment that can be used to get cm level positions with some patience and post processing but can be almost a one man operation if you can pack up the equipment which is mostly a tripod or two.

 

Also computational tools to work geodetically.

 

What I don't seem to have lately is much flexibility in time and to some degree much personal leeway to get away and do these things.

 

Helping others on a contributing basis is about the best scenario for my situation.

 

Finding an old mark is the stuff dreams are made of for surveyors. In my case, a retired one.

 

- jerry

[+jwahl]

PS: My references to SugarLoaf relate to posts from a few years back where I thought there was some ambiguity about an old station versus a new station.

 

It was an example of where if you inversed coordinates in the NGS database you would get conflicting information about where they were from a few other clues.

 

I have not revisited that situation recently but remember it being an intrigue.

 

So I may be out of date on that situation.

 

But it was in a sense a classic investigative case.

 

Seems like I remember a debate that touched on similar issues up in the NY area where there were two stations allegedly 10 feet away from each other by datasheets. But where are they really?

 

- jlw

[+Ernmark]

..the drill hole shown was actually at the possible location of PIVOT - we were unable to scrounge up a drill hole for our target. On the way down we stated no interest in ever going back up there...but.. ...we did muse that having a professional-grade GPSr would certainly narrow the search area! I also would like to see Harpers Ferry from the 'official' overlook (which was a seperate offshoot trail) someday, which we didn't have time (energy) to do at the time...

 

Edit to mention the I didn't realize there were 2 more posts after #25. I'll go back! We may have missed our vegetation window by now...we were probably only a few days ahead of the vegetation Fall/spring again?

 

Would give me time to 'go into training' for the hike...at least we know what we're in for!

Edited April 8, 2010 by Ernmark