Monday, September 14, 2015

Bounding Rectangles - A Case for Something Better

It’s 2015. Almost 2016. And the best we can do to show the extent of a data set is a bounding rectangle?  By their very nature bounding rectangles are not particularly helpful, especially for geographic footprints that are not at all a rectangle. 

Anyone who has searched for, generated metadata for, published, or tried to download geographic data has run into the bounding rectangle.  It is usually displayed in a rather small, set to the side, unusable map graphic. It certainly seems that in this day and age we could do more than that. 

The Alexandria Digital Library Project is almost 20 years old (  This project described a gazetteer for geospatial data that would use a real footprint as a location index that could be embedded in any number of applications. 

What if we could select a basic set of geopolitical boundaries to register our data and the inset map would actually show the boundary of the state, county, city, or park that the data was describing or contained within.  Granted there might be issues in finding an agreeable boundary to use for a city especially with changing annexations and de-annexations and in many parts of the world the boundaries of countries are changing and evolving.  But clearly we should be able to do better than a bounding rectangle.

Maybe we could even develop a method for using a real map to search for available geospatial data. 

Imagine if the Geographic Names Information System (GNIS) ( had more than a point for each name? What if there was also a polygon of the area covered by that name?

While it is relatively simple to link lists of names or point locations to Census geography, shouldn’t it be routine to identify the footprint of published data by the actual data extent?  This could be extended to symbolize the footprint by the date last updated and the data steward or data publisher. 

Maybe it’s time to start thinking outside the bounding rectangle box.

Monday, September 7, 2015

PLSS CadNSDI – PLSS Special Surveys - Mineral Surveys

This is the eighth of a series of documents that describe the contents of the PLSS CadNSDI data set.

A Mineral Survey is a type of PLSS Special Survey. In the seventh document PLSS Special Surveys, ( were discussed in general. The non-rectangular surveys are deviations from the hierarchical rectangular surveys, are often defined or guided by provisions of legislation or authorities.  PLSS Special Surveys can “sit on top” of rectangular surveys or they may replace the rectangular surveys, creating a “hole” in the rectangular surveys.  In some cases a nominal rectangular survey is extended through the special surveys. 

Mineral Surveys

Mineral surveys are made to mark the legal boundaries of mineral deposits or ore-bearing formations on the public domain where the boundaries are determined by lines other than the normal subdivision of the public lands. These surveys include the usual surveying technical procedures and the examination and documentation of various reports and certificates necessary to substantiate legal procedures. (

The manual cited above and several other mineral survey guides are available on line.  This discussion does not cover the survey, recording, or researching procedures.  This document describes how mineral surveys are portrayed in the PLSS CadNSDI and some of the nuances of using this special survey type in the PLSS CadNSDI.

Brief Background

The mineral survey plat and survey notes are sued to compile the polygons seen in the PLSS CadNSDI.  Mineral Surveys were created and recorded to establish a right of entry to extract or process a mineral deposit.  Most mineral surveys are composed of a set of mining claims (claims).  These can be lode claims, placer claims or mile site claims.  The mineral survey is collection of these claims recorded together, but the rights and patents (conveyances out of the federal government to the claimant) occur at the claim level, not the mineral survey level.
Much like a traditional subdivision has individual lots, a mineral survey has claims, a division of the mineral survey, and the operational unit is the claim within the survey. 

The General land Office (GLO) or BLM assigns numbers to the mineral surveys.  Historically, they are uniquely numbered within a mining district and more recently most states have renumbered the mineral surveys providing a unique mineral survey number within the state.  Colorado is the exception and there are duplicated mineral surveys within the state.

The claims within the mineral survey are named or numbered.  The claim name or number can be added to records captured in the parcel fabric and over time it is expected that more of this information will be included in the PLSS CadNSDI.  In some PLSS CadNSDI data sets the claim lines are included the PLSS Intersected feature class, however, for legal uses, users should consult the original records or the state BLM Office.

Figure 1 Sample Mineral Survey Plat with Claims
Accompanying the mineral survey plat is the Mineral Surveyor’s notes, shown in Figure 2.  These contain detail on the metes and bounds measurements of the individual lodes, notes on overlapping claims, exceptions, and conflicts.  This level of detail describing the rights, conflicts, and patent status are not part of the cadastral Framework but may be found on BLM Master Title Plats (MTPs) or Land Status records that describe and portray federal interests in land.

Figure 2 - Example Mineral Survey Notes

Some mineral surveys may be segregated from the rectangular survey with lotting.  Supplemental Survey Plats or occasionally GLO re-lotting plats establish the segregation lots.  Because of the irregularity of the mineral surveys and the patent issues based on claims within the mineral surveys and lots established around the mineral surveys, it is not uncommon to find small slivers of land between mineral surveys that have not been lotted and have not been patented.

Mineral Surveys in the PLSS CadNSDI Special Surveys

In many of the highly complicated mineralized areas, the BLM has not completed the mineral survey abstraction and verification.  In these areas the PLSS CadNSDI may contain stacked aliquot parts, typically the sixteenth (quarter quarter) that represent the general location of the mineral survey.  These aliquot part polygons are NOT the mineral survey boundary.  These polygons serve as a general location of the mineral survey.  In these cases each mineral survey will include the sixteenth part the mineral survey is presumed to be in, so some may be contained entirely within one sixteenth and others may be multiple sixteenth parts.

The small gaps in and around mineral surveys may be identified as unnumbered lots or more correctly as remainder aliquot parts in the PLSS CadNSDI.  The PLSS CadNSDI does not establish the ownership of these gaps. A field survey is necessary to resolve the exact location and size of these gaps and a records search (records verification) is necessary to establish the ownership.  The PLSS CadNSDI shows the mapping differences based on record abstracts.

In the PLSS CadNSDI the rectangular PLSS polygons may be included “under” the Mineral survey areas.  A more extensive records search and even a field survey may be needed to determine of the rectangular PLSS has been vacated with the additional of the mineral survey.  In some states the rectangular PLSS is included for general location for records indexing and in other states the rectangular has been removed and the mineral surveys create a “hole” in the rectangular PLSS.

Because of the nature of mining claims and mineral discovery, mineral claims and mineral surveys may be located in unsurveyed protracted areas of the rectangular PLSS.  That is the mineral survey was done before the rectangular survey and there is no supporting rectangular division to reference the mineral survey. The rectangular polygons in these areas should be treated as planned areas and should not be relied on for legal land description.  The location of the mineral survey in relation to the protracted areas should not be relied upon.

Figure 3 is an example of mineral survey that has been segregated from the rectangular PLSS and all of the claims in the mineral survey have been patented.

Figure 3 - Example of Segregated Patented Mineral Survey

Figure 4 is a mineralized in Utah where some of the mineral surveys have been abstracted and others have not.

Figure 4 - Example of Rectangular Areas Around Mineral Surveys

In this case the rectangular PLSS is provided in areas where the mineral survey has not been abstracted and has been removed under the mineral survey that has been abstracted. The segregation lots have been identified around the mineral survey.

In Figure 5 the PLSS Special Survey class has been added to the map.  The mineral survey labeling indicates that the unabstracted surveys have been assigned to their associated sixteenth or aliquot second division polygon and the exact outline of the mineral survey cannot be discerned in the PLSS CadNSDI. For example in Figure 5, notice that MS142, MS 5582 and MS 5581 have been “mapped” to the NENE aliquot part and MS 6188 is “mapped” to Lot 31.

Figure 5 - Example of Mineral Surveys and Rectangular Areas

Some References
There are many Internet published references for mineral survey procedures and the nuances and details for abstracting and research mineral survey records.  The following is a small sample of some resources.

This is a good guide on the field survey and reporting requirements and methods.

Searching for BLM Records (
This is a web page hosted by the Nevada BLM State Office that provides some guidance on how to search for federal land records

Chapter 10 of the most recent version of the Manual of Surveying Instruction discusses the elements and surveying requirements for mineral surveys.