General Land Office (GLO) Maps of the State of Iowa, as Surveyed from 1836-59, Hamilton County

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Data_Organization_Information
• Spatial_Reference_Information
• Entity_and_Attribute_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: UI - Office of the State Archaeologist

Originator: Iowa Geological Survey, DNR

Originator: University of Iowa Libraries

Publication_Date: 20080129

Title:

General Land Office (GLO) Maps of the State of Iowa, as Surveyed from 1836-59, Hamilton County

Edition: 20080129

Geospatial_Data_Presentation_Form: map

Online_Linkage:

<ftp://ftp.igsb.uiowa.edu/gis_library/counties/Hamilton/GLO_maps_40.tif>

Online_Linkage:

<ftp://ftp.igsb.uiowa.edu/gis_library/counties/Hamilton/GLO_maps_40.zip>

Description:

Abstract:

This is a mosaicked county-wide image (tif format) of georeferenced township maps from the General Land Office (GLO) surveys beginning in 1836 through 1859. The source of the georeferenced images is scanned microfilm of plats from the State Archives. These plats represent maps drawn from the original field notes by the Surveyor General's Dubuque office. This county-wide layer is a Tif format that was created by mosaicing individual township files.

Purpose:

The GLO surveys are a detailed record of Iowa's landscape in the earliest stages of its transformation by Euroamerican settlement and is a significant resource for historians, archaeologists and environmental scientists. The georeferenced GLO maps will be widely available for research and will reduce the usage of and therefore help conserve the microfilm copies, which in many libraries are becoming worn from use. Having the GLOs in a GIS will facilitate locating areas of interests because the user will not have to know the exact township and range designation, but can locate the area of interest by first locating their area with familiar features like towns, roads or farm fields visible in aerial photographs. Then the GLO maps can overlay that area with additional functions like zoom and pan and seamless continuation into adjacent townships. This cannot be done with a microfilm search. Having the GLO maps in a geospatial context will also facilitate the creation of vector data of historical anthropological and landscape features and aid in spatial analyses of phenomena such as settlement patterns.

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 1836

Ending_Date: 1859

Currentness_Reference: ground condition

Status:

Progress: Complete

Maintenance_and_Update_Frequency: As needed

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -93.215410

East_Bounding_Coordinate: -93.087642

North_Bounding_Coordinate: 40.899585

South_Bounding_Coordinate: 40.810774

Keywords:

Theme:

Theme_Keyword_Thesaurus: none

Theme_Keyword: GLO

Theme_Keyword: General Land Office

Theme_Keyword: surface and manmade features

Theme_Keyword: landcover

Theme_Keyword: Euroamerican settlement

Theme_Keyword: historic Native Americans

Theme:

Theme_Keyword_Thesaurus: ISO 19115 Topic Category

Theme_Keyword: imageryBaseMapsEarthCover

Place:

Place_Keyword_Thesaurus:

Counties and County Equivalents of the States of the United States and the District of Columbia (FIPS Pub 6-4)

Place_Keyword: Iowa

Place_Keyword: United States

Place_Keyword: Hamilton Coutny

Temporal:

Temporal_Keyword: 1830's

Temporal_Keyword: 1840's

Temporal_Keyword: 1850's

Temporal_Keyword: historic

Access_Constraints: None

Use_Constraints:

The Office of the State Archaeologist makes no representations or warranties regarding the accuracy or completeness of the information depicted or the data from which it was produced. The information represented is not suitable for: navigational purposes; as evidence used in court of law regarding property disputes; and does not purport to depict or establish boundaries between private and public land.

The development of the coverages in the NRGIS Library represents a major investment of staff time and effort. As a professional responsibility, the Iowa DNR expects to receive proper credit when these GIS coverages are utilized. The Department also expects that the original documentation will remain with any redistribution of these coverages.

Point_of_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Joe Artz

Contact_Organization: UI- Office of the State Archaeologist

Contact_Position: GIS Coordinator

Contact_Address:

Address_Type: mailing and physical address

Address: 700 S. Clinton St. Bldg.

City: Iowa City

State_or_Province: IA

Postal_Code: 52240

Country: USA

Contact_Voice_Telephone: 319-384-0795

Contact_Electronic_Mail_Address: joe-artz@uiowa.edu

Hours_of_Service: 8:00 AM - 4:30 PM

Data_Set_Credit:

Melanie Riley, Joe Artz, Sally Hakes, Pete Kollasch, Jim Giglierano, and Casey Kohrt are a recognized as contributing to this project.

Native_Data_Set_Environment:

Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.2.2.1350

Cross_Reference:

Citation_Information:

Originator: Department of Landscape Architecture, Iowa State University

Title:

General Land Office Research - GLO Project - Iowa State University

Other_Citation_Details:

A significant amout of research has been done on the GLO maps by this Project

Online_Linkage: <http://www.glo.gis.iastate.edu/pinfo/pro_info.html>

Data_Quality_Information:

Logical_Consistency_Report:

All GLO township maps in the collection were georeferenced in NAD 83 UTM Zone 15 using county mosaic DRGE's of USGS 1:24000 topo maps as base maps.

Two methods were used in georeferencing the township maps largely due to a change in software versions during the project. The first method used ArcInfo 9.0, with control points set at every section corner and using 3rd order polynomial transformation. The area using the first method is primarily the eastern third of the state where the greatest concentration of anthropological features occur on the maps and alignment was the most critical. The area includes the following counties and all of the counties east: Mitchell, Chickasaw, Bremer, Black Hawk, Benton, Iowa, Dallas, Warren, Monroe, eastern half of Wayne. Western counties' townships georeferenced with this method include: Fremont, Mills, Pottawattamie and Harrison.

The second method used ArcInfo 9.2, control points at the section corners of the township boundary only and Spline for the transformation. The area produced from this method is primarily the south central and western counties where map features were much less dense. These counties include: west half of Wayne, Lucas, Madison, Decatur, Ringgold, Taylor, Adams, Cass, Montgomery, Page, Monona, Woodbury and Plymouth.

Completeness_Report:

Missing townships in Lee Co.: T66NR04W, T66NR05W, T66NR06W, T66NR07W, T65NR04W, T65NR05W, T65NR06W. These townships were part of the Half-Breed Tract and were not included in this GLO survey, but in another government survey in 1832 (Source: <http://www.glo.gis.iastate.edu/pinfo/timeline.html>). Missing townships T81NR27W in Dallas Co., T84NR47W, T85NR46W, T85NR47W in Monona Co., T86NR45W, T87NR45W, T88NR45W, T89NR45W in Woodbury Co., and T90NR45W, T91NR45W, T92NR45W, T93NR45W in Plymouth Co.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

Scanned microfilm of the original GLO township plats were georeferenced by their section corners. Features such as section corners are only as accurate as the survey that determined their location. The GLO survey maps were not created under a national map accuracy standard and the survey itself was conducted by 187 deputy surveyors introducing the possibility of variable accuracy (Source: <http://www.glo.gis.iastate.edu/pinfo/timeline.html>). The images used for georeferencing are 3rd generation and have been prone to distortion through microfilm production, scanning of the microfilm and rubber sheeting. Therefore, adherence to NMAS for this project cannot be claimed nor accuracy can be calculated in this situation. It is also important to note that features within the section boundaries were not surveyed, but drawn from notes of their existence and field sketches. For example, stream channels were improvised between their crossing at one surveyed boundary to another.

Lineage:

Process_Step:

Process_Description:

New microfilm was created of the GLO plats at the State Archives. The microfilm was then scanned into bitmapped tiff files by Heritage Microfilm, Cedar Rapids, IA. The tiff files were saved onto an external hard drive which was lended to the Office of the State Archaeologist (OSA). This step was under the supervision of the Univerity of Iowa libraries.

Process_Date: 20070201

Process_Step:

Process_Description:

The images on the external hard drive were renamed at the Office of the State Archaeologist by legal township designation. The images were then copied to the OSA's server and the hard drive with the renamed images given back to the University libraries where they will be adding the images to the Iowa Digital Heritage Collections.

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Melanie Riley

Contact_Organization: UI - Office of the STate Archaeologist

Contact_Position: GIS Specialist

Contact_Voice_Telephone: 319-384-0604

Contact_Electronic_Mail_Address: malanie-riley@uiowa.edu

Process_Step:

Process_Description:

The OSA then clipped away the information that was not part of the actual township map in Adobe Photoshop 7.0.1 and cleaned marks in the map caused by dust, scratches and hair recorded in the imagery. Map imagery that went outside of the township boundary was preserved. This included items such as cabins, fields, names and Native American features. Many times, the feature is not replicated on the adjacent township but only exists in the outside margins of the township plat. If a feature outside the township boundary overlapped with the same feature recorded inside its proper township, then the extra pixels were cleaned up using ArcScan. This method was used for the eastern third and the far southwest corner of Iowa were anthropological features were the densest.

Process_Step:

Process_Description:

Most images were georeferenced using ArcInfo 9.0. Control points were set at all the section corners between the GLO plats and the base map (county mosaic DRGE of USGS 1:24000 topo maps). Section corner match between the GLO map and base map is within +/- 50 feet 90% of the time for most counties. A few counties, such as Delaware, have such skewed section lines that 3rd order polynomial transformation was not very effective. Also please refer to the discussion of horizontal positional accuracy.

Images were rectified as tif's with cell size of 4 m. The rectified images were then uploaded to the Iowa Geological Survey ftp site.

Process_Step:

Process_Description:

Due to unforeseen events, the process was changed for some south central and western counties. The second method used ArcInfo 9.2, control points at the section corners of the township boundary only and Spline for the transformation. The area produced from this method is primarily the south central and western counties where map features were much less dense. These counties include: west half of Wayne, Lucas, Madison, Decatur, Ringgold, Taylor, Adams, Cass, Montgomery, Page, Monona, Woodbury and Plymouth.

Due to a bug in ArcGIS 9.2 that has not been fixed yet with service pack 3, a work around had to be implemented that adds a few more process steps than what is required for normal georeferencing. The work around steps are posted on the ESRI forum at ArcGIS Desktop - Raster display and management <http://forums.esri.com/Thread.asp?c=93&f=1740&t=209585> under the posting by Melanie Riley.

Process_Step:

Process_Description:

Mosaicing was done at the Iowa Geological Survey. The individual township maps included some 1 bit datasets, some 8 bit datasets, all with lines as value zero and background as one. These were mosaicked together with ArcMap 9.2 into a statewide 2 bit dataset using a minimum function to give lines priority. The values were then remapped into a 2 bit dataset shifting lines to value 2, with background still one. Areas outside a narrow buffer around the state were clipped to value zero.

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Pete Kollasch

Contact_Organization: Iowa Geological Survey, DNR

Contact_Voice_Telephone: 319-335-1578

Contact_Electronic_Mail_Address: pete.kollasch@dnr.iowa.gov

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Raster

Raster_Object_Information:

Raster_Object_Type: Pixel

Row_Count: 2460

Column_Count: 2688

Vertical_Count: 1

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Planar:

Grid_Coordinate_System:

Grid_Coordinate_System_Name: Universal Transverse Mercator

Universal_Transverse_Mercator:

UTM_Zone_Number: 15

Transverse_Mercator:

Scale_Factor_at_Central_Meridian: 0.999600

Longitude_of_Central_Meridian: -93.000000

Latitude_of_Projection_Origin: 0.000000

False_Easting: 500000.000000

False_Northing: 0.000000

Planar_Coordinate_Information:

Planar_Coordinate_Encoding_Method: row and column

Coordinate_Representation:

Abscissa_Resolution: 4.000000

Ordinate_Resolution: 4.000000

Planar_Distance_Units: meters

Geodetic_Model:

Horizontal_Datum_Name: North American Datum of 1983

Ellipsoid_Name: Geodetic Reference System 80

Semi-major_Axis: 6378137.000000

Denominator_of_Flattening_Ratio: 298.257222

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Attribute:

Attribute_Label: Count

Attribute:

Attribute_Label: ObjectID

Attribute_Definition: Internal feature number.

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Unrepresentable_Domain:

Sequential unique whole numbers that are automatically generated.

Attribute:

Attribute_Label: Red

Attribute:

Attribute_Label: Value

Attribute:

Attribute_Label: Green

Attribute:

Attribute_Label: Blue

Distribution_Information:

Distributor:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Iowa Geological Survey, DNR

Contact_Position: GIS Librarian

Contact_Address:

Address_Type: mailing and physical address

Address: 109 Trowbridge Hall

City: Iowa City

State_or_Province: IA

Postal_Code: 52242

Contact_Voice_Telephone: 319-335-1575

Contact_Electronic_Mail_Address: gis_library@igsb.uowa.edu

Resource_Description: Downloadable Data

Distribution_Liability:

Although efforts have been made in correcting errors in order to make this information useful to the Department, the Department assumes no responsibility for errors in the information. Similarly, the Department assumes no responsibility for the consequences of inappropriate uses or interpretations of the data made by anyone to whom this data has been made available. The Department bears no responsibility to inform users of any changes made to this data. Anyone using this data is advised that precision implied by the coverage may far exceed actual precision. Comments on this data are invited and the Department would appreciate that documented errors be brought to staff attention.

Standard_Order_Process:

Digital_Form:

Digital_Transfer_Information:

Format_Name: Tiff Image

File_Decompression_Technique: zip

Transfer_Size: 0.000

Digital_Transfer_Option:

Online_Option:

Computer_Contact_Information:

Network_Address:

Network_Resource_Name:

<ftp://ftp.igsb.uiowa.edu/gis_library/counties/Hamilton/GLO_maps_40.tif>

Network_Resource_Name:

<ftp://ftp.igsb.uiowa.edu/gis_library/counties/Hamilton/GLO_maps_40.zip>

Access_Instructions:

both links need to be downloaded. zip file contains world file and others.

Metadata_Reference_Information:

Metadata_Date: 20080110

Metadata_Review_Date: 20080110

Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Iowa Geological Survey, DNR

Contact_Position: GIS Librarian

Contact_Address:

Address_Type: mailing and physical address

Address: 109 Trowbridge Hall

City: Iowa City

State_or_Province: IA

Postal_Code: 52240

Contact_Voice_Telephone: 319-335-1575

Contact_Electronic_Mail_Address: gis_library@igsb.uiowa.edu

Hours_of_Service: 8:00 AM - 4:30 PM

Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata

Metadata_Standard_Version: FGDC-STD-001-1998

Metadata_Time_Convention: local time

Metadata_Extensions:

Online_Linkage: <http://www.esri.com/metadata/esriprof80.html>

Profile_Name: ESRI Metadata Profile