On October 18, 2022 Lawrence University conducted a geophysical survey on the southwestern side of the Christ Evangelical and Reformed Church cemetery (BTW-0056) in Germantown, Wisconsin. High-resolution magnetic data were conducted over a 20 meter by 40 meter grid to determine if unmarked interments were present in the cemetery. The survey identified a number of magnetic anomalies that appear to be consistent with the presence of unmarked interments. It is recommended that any ground disturbance in the cemetery proceed under the expectation that interments might be disturbed

Peregrine, Peter N.

English

Lawrence University

Lawrence University Lux Archaeological Reports Anthropology Department 1-2023 Geophysical Survey of the Christ Evangelical and Reformed Cemetery, Germantown, WI BWT-0056 Peter N. Peregrine Follow this and additional works at: https://lux.lawrence.edu/archaeological_reports  Part of the Archaeological Anthropology Commons © Copyright is owned by the author of this document. This Archaeological Report is brought to you for free and open access by the Anthropology Department at Lux. It has been accepted for inclusion in Archaeological Reports by an authorized administrator of Lux. For more information, please contact colette.brautigam@lawrence.edu.   LAWRENCE UNIVERSITY ARCHAEOLOGICAL REPORTS NUMBER THIRTEEN     JANUARY 2023  PETER N. PEREGRINE, DIRECTOR         Geophysical Survey of the Christ Evangelical and Reformed Cemetery, Germantown, WI BWT-0056  Peter N. Peregrine, Lawrence University January, 2023  Final Report  Abstract:  On October 18, 2022 Lawrence University conducted a geophysical survey on the southwestern side of the Christ Evangelical and Reformed Church cemetery (BTW-0056) in Germantown, Wisconsin.  High-resolution magnetic data were conducted over a 20 meter by 40 meter grid to determine if unmarked interments were present in the cemetery.  The survey identified a number of magnetic anomalies that appear to be consistent with the presence of unmarked interments.  It is recommended that any ground disturbance in the cemetery proceed under the expectation that interments might be disturbed.          Contents  Introduction and Context ................................................................................................................ 1 Methods........................................................................................................................................... 1 Results of Investigations ................................................................................................................. 2 Recommendations ........................................................................................................................... 3 References ....................................................................................................................................... 4 Figures............................................................................................................................................. 5 Figure 1: General location of the Christ Evangelical and Reformed Cemetery (BWT-0056) within the State of Wisconsin. ................................................................................................................................................................. 5 Figure 2: USGS 7.5 minute quad image showing the location of BWT-0056, the Christ Evangelical and Reformed Cemetery. .................................................................................................................................................................. 6 Figure 3: Aerial image of the Christ Church Cemetery, showing lot lines. ............................................................... 7 Figure 4: Aerial image showing the geomagnetic survey area (outlined in yellow). ................................................ 8 Figure 5: Geomagnetic data superimposed on an aerial image of the Christ Church Cemetery. .............................. 9 Figure 6: Geomagnetic anomalies that appear consistent with possible unmarked interments (identified with green dots). ........................................................................................................................................................................ 10 Figure 7: 1950 aerial image of the Christ Church Cemetery showing small trees growing in the survey area. ...... 11 Figure 8: Geomagnetic anomalies that appear to be arranged in a curvilinear pattern (identified with dashed yellow lines) similar to those of the marked interments to the west of the survey area. ......................................... 12 Figure 9: Possible interments (green dots) and linear patterns (dashed yellow lines) identified within the survey area. ......................................................................................................................................................................... 13         1  Introduction and Context  The research reported here was undertaken by the request of the Germantown Historical Society.  The Society manages Christ Evangelical and Reformed Church, located at the intersection of Highway 145 and Holy Hill Road in the Southwest Quarter of Township 9, Range 20 East, Section 8 (Figures 1 & 2).  The congregation was organized in 1842, and in 1850 constructed a log church on land donated by Philip Dhein in a small settlement that came to be known as Dheinsville (Quickert 1923).  The existing church was built in 1862 on the same site, and is on the National Register of Historic Places as an example of Gothic Revival ecclesiastical architecture of local significance (NRHP Reference #83004324).    Adjacent to the church is a small cemetery with interments dating from 1854 to 2021 (Figure 3).  Members of the Germantown Historical Society believe that unmarked interments were disturbed during the reconstruction of Hwy 145, which sits adjacent to the eastern side of the cemetery.  There are two marked interments located on the edge of, or possibly within, the highway right-of-way, suggesting that interments might indeed have been disturbed.  If so, they were not reported to the State Historic Preservation Officer or their disturbance mitigated.  In response to this concern, a Phase I investigation was performed in 2008 in advance of utility work along the highway.  No interments were located, though the investigator recommended further monitoring (Harvey 2008).  Methods  Geomagnetic survey was conducted over two 20 meter by 20 meter grids covering the area where possible unmarked internments were thought to be located (Figure 4).  Geomagnetic data were collected using a Geoscan FM256 differential gradiometer (Geoscan Research 2009).  This instrument consists of two magnetometers arranged one atop the other with a 0.5 meter separation.  Each magnetometer measures the earth’s magnetic field and the difference between the two readings, which is equivalent to the vertical gradient of the earth’s magnetic field, is recorded.  The instrument is sensitive enough to measure tiny variations in the earth’s magnetic field, variations that might be caused by subtle soil changes or the presence of buried materials (Aspinall, Gaffney, and Schmidt 2009).  For this application sensitivity of the FM256 was set at 1.0 nanotesla, or about 1/25,000th of the earth’s total magnetic field.  Data were collected at 0.25 meter intervals along 0.5 meter spaced parallel northeast-southwest lines and using a zig-zag method.    The raw magnetic data were downloaded from the FM256 into the Geoplot 4.0 software package (Geoscan Research 2016).  Analyses conducted on the data involved (in the following order) (1) “clipping” to remove high and low data points more than one standard deviation from the mean; (2) “despiking” to remove any point source data spikes; (3) “zero mean traverse” and “zero mean grid” to balance the data values across the separate grids; (4) “destaggering” to bring individual transects into proper alignment; (5) “low pass filtering” based on immediately surrounding measurements to enhance weak magnetic features; and (5) “interpolation” conducted once in the X direction to make each pixel represent 25 square centimeters.  The image resulting from this  2  processing is presented in Figure 5.  Magnetic highs appear as darker grays; magnetic lows as lighter grays.  Results of Investigations  The basic assumption underlying the interpretation of geomagnetic data is that the survey area has a uniform magnetic character.  Deviations from that uniform pattern suggest the presence of buried objects or features with a different magnetic signature.  The focus of interpretation is these magnetic anomalies.  Interpreting anomalies is as much an art as it is a science.  The analyst uses mathematical manipulation of the data and alters the color and contrast of the related geomagnetic map to isolate features with specific magnetic characteristics or that seem to form patterns of interest.  In the case of unmarked interments, the analyst looks for anomalies that are oblong in shape, roughly 3 meters by 2 meters in size, and oriented East-West, as these are the shape and orientation of most cemetery interments in the United States (Strangstad 2013).  Such anomalies are also expected to be arranged in linear patterns or some other regular pattern reflecting planned placement within the cemetery’s organizational blueprint.    In addition to shape and orientation, previous research suggests that interments without a coffin or casket (a coffin is angled toward the head and feet, while a casket is square) have a magnetic signature of between 5 and 15 nanotesla, compared to the surrounding soil (e.g. Peregrine 2016).  This magnetic signature is due to the presence of metal objects used to construct the coffin or casket and metal objects on the interred individual.  The decay of organic material can also impart a small magnetic moment to soils.  Interments in metal caskets, which became ubiquitous in the early 20th century (Haberstein and Lamers 2014), have much higher magnetic signatures, sometimes higher than the maximum reading of the FM 256 gradiometer (2400 nanotesla).  This makes metal caskets easy to locate, but their strong magnetic field also masks all other magnetic signatures in an area roughly 3 to 5 square meters around the metal casket.  Figure 6 indicates with green dots those anomalies that appear consistent with unmarked interments.  Note that some of the dots mark known interments, which provides some confirmation that the identified anomalies are consistent with other interments in the Christ Church Cemetery.  That these anomalies are consistent with known interments does not mean such interments are actually present, as there are other disturbances that might cause similar anomalies.  For example, Figure 7 shows an aerial image of the Christ Church Cemetery taken in 1950.  Note the small trees scattered across the survey area.  Some of the anomalies marked in Figure 6 may be the decayed stumps of these or other plantings that once grew in the cemetery.  However, Figure 8 indicates that many of the anomalies appear to lie along curved lines that are similar to the spacing and curvature of the marked interments further to the west.  This pattern is unlikely to be the sole result of tree placement or other natural disturbances.  It seems more likely that they represent unmarked interments.  These are shown without the geomagnetic data in Figure 9.     3  Recommendations  1. The Germantown Historical Society should, in consultation with the State Historical Society of Wisconsin, act to preserve intact the entire area within the boundaries of the Christ Church Cemetery.  2. The Germantown Historical Society should, in consultation with the State Historical Society of Wisconsin, undertake Phase II investigations in advance of any construction, landscaping, or other ground disturbance within the boundaries of the Christ Church Cemetery.  3. The Germantown Historical Society should, in consultation with the State Historical Society of Wisconsin, have additional non-invasive surveys conducted within the boundaries of the Christ Church Cemetery in order to more precisely identify and locate potential unmarked interments.        4  References  Quickert, Carl 1923 The Story of Washington County.  Privately published.  David, Andrew, Neil Linford, and Paul Linford, eds. 2008 Geophysical Survey in Archaeological Field Evaluation.  Swindon, UK: English Heritage.  Geoscan Research 2009 Instruction Manual, Fluxgate Gradiometer FM 256.  Bradford, UK: Geoscan Research.  Geoscan Research. 2016 Geoplot 4.0 Instruction Manual. Bradford, UK: Geoscan Research.  Haberstein, Robert and William Lamers 2014 The History of American Funeral Directing, (8th Edition).  Brookfield, WI: National Funeral Directors Association of the United States.  Harvey, Jennifer 2008 Archaeological Investigations for the Maple New Feeder Project Area, Washington County, Wisconsin.  Manuscript on file at the Wisconsin State Historic Preservation Office.  Peregrine, Peter N.  2016 "Geophysical Survey of Wisconsin Burial Site OU-0069: Grand Chute Pioneer Cemetery". Lawrence University Archaeological Reports 8.  https://lux.lawrence.edu/archaeological_reports/8  Strangstad, Lynette 2013 A Graveyard Preservation Primer, (2nd Edition).  Lanham, MD: Alta Mira.    5  Figures  Figure 1: General location of the Christ Evangelical and Reformed Cemetery (BWT-0056) within the State of Wisconsin.      6   Figure 2: USGS 7.5 minute quad image showing the location of BWT-0056, the Christ Evangelical and Reformed Cemetery.          7   Figure 3: Aerial image of the Christ Church Cemetery, showing lot lines.         8   Figure 4: Aerial image showing the geomagnetic survey area (outlined in yellow).        9   Figure 5: Geomagnetic data superimposed on an aerial image of the Christ Church Cemetery.          10   Figure 6: Geomagnetic anomalies that appear consistent with possible unmarked interments (identified with green dots).          11   Figure 7: 1950 aerial image of the Christ Church Cemetery showing small trees growing in the survey area.         12  Figure 8: Geomagnetic anomalies that appear to be arranged in a curvilinear pattern (identified with dashed yellow lines) similar to those of the marked interments to the west of the survey area.           13   Figure 9: Possible interments (green dots) and linear patterns (dashed yellow lines) identified within the survey area.        

Geophysical Survey of the Christ Evangelical and Reformed Cemetery, Germantown, WI BWT-0056

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Geophysical Survey of the Christ Evangelical and Reformed Cemetery, Germantown, WI BWT-0056

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