Define "hydrographic Mark"

[+Firefighter Skippy]

I'm looking for a description of what a "hydrographic mark" is. It's lasted as the BM for LX6514 but I'm not sure what I should look for. any help would be appreaciated.

[+Spoo]

According to my 1940 edition of SURVEYING, by Davis and Foote:

 

A 'hydrographic mark' can be any of several things pertaining to the measurement of a body of water. They can be used for finding the topography of a shore or bank, or for measuring the elevation of a body of water.

 

Hydrographic marks were also used for determining tide heights and level changes in lakes and rivers.

 

They are also used for irragation grades and for measuring discharge from streams.

 

Edit note: Firefighter Skippy.......It is interesting to see that the U S Power Squadron declared this mark found without any comment even though the USGS declared it was probably lost 30 years earlier. Have you gone to look for it yourself? It would appear that it is a standard disk mounted in the top of a seawall.

Edited March 13, 2006 by Spoo

[+Firefighter Skippy]

Thanks for responding spoo. Yes, I did look for it. About 200' from GZ in/on a rock I found an etched square with a @1/2" drill hole in it's dead center. Discription didn't seem to mention a disc but a "hydrographic mark". Ergo, I thought this square might be the mark.

[+Spoo]

I stand corrected.....I re read the description and it does not say a disk.

 

LX6514 STATION DESCRIPTION

LX6514

LX6514'DESCRIBED BY COAST AND GEODETIC SURVEY 1934 (GCM)

LX6514'THIS STATION IS LOCATED IN THE SEA WALL, S OF BEACH STREET IN

LX6514'THE EASTERN PART OF THE SAVIN ROCK DISTRICT. IT IS 5.2 METERS S

LX6514'OF THE S CURB OF BEACH STREET AND ON LINE WITH THE S FACE OF THE

LX6514'EASTERLY PART OF THE SEA WALL.

LX6514'

LX6514'A STANDARD HYDROGRAPHIC MARK WAS SET IN THE SEA WALL AT THIS

LX6514'POINT. OTHER MEASUREMENTS ARE SHOWN IN THE SKETCH.

LX6514'

LX6514'STATION WAS DETERMINED BY A 3-POINT FIX WITH CHECK.

LX6514

 

Allow me to make a guess here....and hope one of our experts steps in......

 

1934 sure seemed to love brass disks.....so I still think that might have been the main mark. The description says "a 3 point fix".....so I wonder if you found one of the reference points used to center the main mark location. I have found drill holes used as reference points around here.

 

LX6514 STATION RECOVERY (1954)

LX6514

LX6514'RECOVERY NOTE BY US GEOLOGICAL SURVEY 1954

LX6514'STATION BELIEVED DESTROYED, SEA WALL DAMAGED AT THIS POINT.

 

The sea wall could easily have been made of rocks as opposed to concrete. In 1954 they report the sea wall is damaged at this location.......seems hard to believe that your rock was part of the seawall and was moved with the mark still up and still in place after so many years, again leading me to think it might have been a reference point. What is the seawall made of now?

 

LX6514 STATION RECOVERY (1987)

LX6514

LX6514'RECOVERY NOTE BY US POWER SQUADRON 1987 (MK)

LX6514'RECOVERED IN GOOD CONDITION.

 

This does not mean anything. The USPSQD is notorious for driving to a location, looking out the window and logging the general area as 'the mark'. It is also possible they found your chiseled mark with hole and without doing the research that you are, just claimed the find. They also never seem to give any info that would help the next person find these things.

 

The initial log notes a sketch. You might try contacting the NGS and see if they can provide you with a copy of that sketch. (What a treasure !!) I should think it would clearly spell out what marks were used for the MAIN and REFERNCE locations and given one, you might find the whole darn mess !

 

Good Luck to you and have fun with this!

 

Spoo