GPR Data LLC was contacted by Dave Cotner Senior from Lakeside, Oregon in April of 2007 with regard to gpr services for mapping a buried Chinese Junk that was deposited on the Oregon coast in the early 1400’s by a tsunami originating off the coast of New Zealand. Site conditions, terrain, depth of investigation, subsurface composition, and accessibility were discussed. GPR Data LLC proposed a preliminary site evaluation, as standard practice, to determine the feasibility of GPR, test survey the proposed location, and acquire exact site and subsurface conditions to foreword model the data acquisition plan for this site. This preliminary evaluation was conducted on May 2, 2007 by GPR Data LLC personnel Mike Edwards, Matthew Edwards, and Thomas Royer. Following the preliminary study, a date was set to procure data acquisition on May 22, 2007. This survey was witnessed and observed by Dave Cotner Jr., Dave Cotner Sen., and Gavin Menzies, author of the book, 1421 The Year The Chinese Discovered America.

GPR Data LLC extends a great thanks to 1421, Gavin Menzies, Dave Cotner Sen., and Dave Cotner Jr. for allowing us to provide geophysical evidence to help aid the foreword progress of the project. We are honored to be a part of something with such great magnitude and discovery.

Equipment and Profiles

A SIR-3000 (Subsurface Interface Radar) system was used with a 200 MHz and 400 MHz antenna. The system, antenna, and survey wheel used, were calibrated on site according to local conditions. A 200 MHz and 400 MHz deep penetration profile was used with the target window at 150 nanoseconds; and target depth approximately 40-60 ft. deep were achieved. A relative dielectric was set at 3.09. Using velocity analysis, a standard post-processing procedure, we were able to calculate accurate depths and dimensions for features of interest after the survey was completed.

Each data profile was processed using Radan NT. 6.5007 for Windows software. Each data profile was looped into a 3D model. These models were analyzed using 3D depth slices. The identity of any areas of interest, or subsurface features was noted and analyzed further. A terminal depth, and slope bottom was set at 60 ft. Markers were placed on any targets above this terminal depth within each 3D data model.

Preliminary GPR Evaluation Methodology

A rectangular grid 60 ft. wide and 160 ft. long was positioned off a gps coordinate obtained from Dave Cotner Sen. Profiles were positioned to encompass a 30 linear ft. radius around this gps coordinate, this ensured all potentially useful information in the gpr survey was captured. The subsurface soils were consistent fine grained beach sand. A fresh water interface was noted at 9 ft. deep. The topography was flat, rising in elevation slightly to the north east. The weather was overcast and slightly rainy; the site had been well saturated with rain on the previous night.

GPR Evaluation Methodology

The survey area was positioned directly over the wreck site using Dave Cotner Sen., his MAS system, and preliminary gpr survey models provided by GPR Data LLC. The dimensions were divided into two grids, one grid with dimensions 80 ft. by 100 ft., labeled area A, and the other grid with dimensions 80 ft. by 50 ft., labeled area B. Data profiles were collected using a standard Cartesian coordinate system, on two ft. intervals. GPR Data LLC used a 400 MHz antenna on the larger grid, labeled area A, and a 200 MHz antenna on area B. The 400 MHz antenna provides greater resolution in areas where the distance from surface to the target was not greater than 35 ft.

Findings

After completing the analysis and interpretation of data profiles that were obtained on May 22, 2007 in Winchester Bay, Oregon, we have summarized the following findings; the main portion of the junk is contained in area A, and a broken chunk of the junks bow and masts along with various other items are contained in area B. We base our findings on information provided by Dave Cotner Sen., Gavin Menzies, and the following gpr data.

1. Using the drawing of the Junk produced by Dave Cotner Sen. as a known reference for the dimensions, physical characteristics, orientation, and location, of this junk, 3D data models and amplitude maps, obtained from gpr profiles confirms the presence of a large high amplitude zone between 25 ft. and 55 ft. deep.
2. A 3D depth slice hows the debris field surrounding the high amplitude zone, as described in area A. An outline of the junk is obtained by point reflection markers.
3. A data slice at 19 ft. deep confirms a linear target. The dimensions are consistent with the mast the junk, and the approximate location provided by Dave Cotner Sen. This feature is positioned in sand at a slight angle and can be seen in a line scan mode as a linear round target.
4. A 2D amplitude map of area A shows amplitude values at 26 ft. deep with 4 ft. target window, it appears that the main body of the junk is contained in area A, and a broken off chunk of the ships bow is contained in area B.

With significant site upgrades coming soon, it was crucial for the El Dorado Hills Irrigation District to have accurate maps of all buried utilities and potential risks. With site hazards such as chlorine gas piping, blind excavation was simply not an option. GPR Data LLC was chosen to create these highly accurate as-builts.

Equipment and Profiles

To meet the range of terrain within the site, both the SIR-20 and SIR-3000 systems were used for various surveys. All survey grids were collected with a 400 MHz antenna, with survey wheels calibrated on-site directly to each individual grid. Each data profile was then processed with the RADAN 6.5 for Windows software, looped into a 3d model, and analyzed via 3d depth/z slices. Velocity migration and a full gambit of post-processing filters were utilized to convert the raw data into highly accurate and usable 3d models of the target grid areas.

Preliminary GPR Evaluation Methodology

Thirteen collection grids of varying dimensions were established to encompass all requested survey regions, as shown in the diagram to the right. Each grid was set on one-foot centers, such that unique line scan profiles were collected at each one foot interval. All grids were demarked on-site with semi-permanent fixtures -- pins, stakes, and survey flags -- to provide easy reference later.

GPR Collection Methodology

Each survey grid was collected independently, with the SIR systems and survey wheel recalibrated to match the local conditions at that time. As the surveys were collected over a period of two weeks, there were a wide variety of weather and soil conditions present. Additionally, there were a wide range of surface and subsurface conditions within the facility itself. This ensured that any lack of attention to system configurations could compromise our ability to later convert the raw data into practical information.

Tucked away in a high valley in the Wallowa Mountains, Enterprise and Joseph celebrate their rich history and amazing landscape. This valley is the homeland of Chief Joseph. The townspeople are friendly and helpful, and they preserve the region's history. When a pioneer-era cemetery was ravaged by wildfire, they enlisted GPR Data LLC to help with recovery.

The Problem

The Alder Slope Cemetery was founded by 1870 at the latest, and most gravesites were marked out with wooden crosses and other fixtures of remembrance. Only a small portion had been demarked with headstones when fire ripped through the cemetery. The historical society retained records of most internments, but had no way to place them at precise physical locations.

The Results

GPR Data LLC used 270 MHz and 400 MHz antennas to first create a 3d map of the cemetery, then identify dominant rows of graves, and finally mark out all cooresponding locations. Each identified target was marked with a flag at the presumptive head, and paint along the trench, for semi-permanent but easily removed reference. Finally, a reference map was built upon satellite imagery to give an overview perspective (right)