Mystery Cache

The Tiffin History Series - Surveying the Land

A cache by IowaPuzzler Send Message to Owner Message this owner
Hidden : 09/18/2011
In Iowa, United States
2.5 out of 5
2 out of 5

Size: Size: micro (micro)

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Geocache Description:

The Tiffin History Series - Surveying the Land

This geocache is not located at the posted coordinates. To determine the location of the geocache you will have to do learn a few facts about land surveying, the location of Tiffin, and the areas original land owners.

Iowa was part of the lands surveyed following the Louisiana Purchase. This effort was done using the Public Land Survey System (PLSS). Using this system, land areas are numbered by township, range and section. Each township is a six-mile square block of land, divided into 36 one-mile squares called sections. Townships are numbered with a north/south value, starting from a specific reference point. The Range refers to an east/west value for the township, starting from the same reference point.

1. The first piece of information you must find is the GPS coordinates of the reference point (or initial point) used for this survey. Several initial points exist within the U.S., but only one was used for the survey where Tiffin lays. Note: Value used is converted (and rounded) to decimel minutes from degrees/minutes/seconds.

There are easy ways to overlay the U.S. Township/Section grid on Google Earth. This is not necessary for the next step, but if you do you will notice that the City of Tiffin is almost exactly one section of a township.

If you do happen to put an overlay on Google Earth, make sure to look around a bit. Its very interesting how the choice of surveying has influenced the development and appearance of the United States landscape.

2. The second piece of information you must find is the identifying information for the section where Tiffin is located. This includes the Township, Range and Section numbers.

Save these numbers for the final step. a = township number b = range number c = section number

The General Land Office (GLO) was responsible for the surveying and sale of public lands. A section (1/36th) of a township is 1 square mile in area, or 640 acres. When these lands were sold (to the public) or given away (to former military members, or part of the Homestead Act), this was often done in "quarter sections" (160 acres) or "quarter of a quarter sections" (40 acres). Hence the term "40 acres and a mule", which refers to receiving 40 acres of surveyed land to create a farm. When ownership of public land was transfered from the government, the GLO issued a Land Patent. These original Land Patents are available on the Bureau of Land Management's web site.

Use the information from step 2 at to view the records of the original land owners of the section that is now Tiffin. You will find that 8 land patents were issued for this section of land.

3. Of the two land grants that were first issued within this section, use the one with the greater land area for the final pieces of information.

  • What year was the land patent issued?
  • What is the certificate/document number?
  • How many acres were purchased?

defg = year of patent (i.e. year 1985 -> d=1 e=9 f=8 g=5)

h = certificate number

i = acres purchased

Note: The document is fairly blurry, but readible. Other patents on the web site are written almost identically and are more readable, they may help to decipher some of the wording. There is also a type'd description that accompanies each grant with the vital information.

Note: This earliest grant corresponds to the land that contains most of the original streets and housing for Tiffin before the town began expanding.

Note: You might be interested to look at some of the other patents for this section. One of the 40 acre patents was given to a retired military man that was active during the war of 1812.

The cache is located at the southwest corner of the land patent from step 3. For the exact coordinates use the information found in steps 1-3.

First calculate the following offset coordinates:

[degrees] = b
[whole minutes] = i / a + d
[decimel minutes] = ( h - f + d ) / e - ( c + d )

[degrees] = g * a - ( f - d ) * i
[whole minutes] = a - e * g + f
[decimel minutes] = c * i - h - a * g - d - f

Now, take the offset coordinates and add the degres and minutes to those of the reference point discovered in step 1. This is where you will find the cache.

You can check your answers for this puzzle on

Additional Hints (No hints available.)



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Last Updated: on 03/20/2014 19:12:32 Pacific Daylight Time (02:12 GMT)
Rendered From:Unknown
Coordinates are in the WGS84 datum