Bedrock Surface Topography Digital Elevation Raster of Pennsylvania


Identification_Information:
Citation:
Citation_Information:
Originator:Pennsylvania Geological Survey, Pennsylvania Department of Conservation and Natural Resources
Publication_Date:20230518
Title:
Bedrock Surface Topography Digital Elevation Raster of Pennsylvania
Edition:1
Geospatial_Data_Presentation_Form:remote-sensing image
Series_Information:
Series_Name:Data Release
Issue_Identification:23-01.0
Other_Citation_Details:
Suggested citation: Guiseppe, A. C., and Ebersole, C. M., 2023, Bedrock Surface Topography Digital Elevation Raster of Pennsylvania: Pennsylvania Geological Survey, 4th ser., DR 23-01.0, scale 1:500,000, raster image.
Description:
Abstract:
PaGS assembled 214,851 relevant well records from Pennsylvania, GroundWater Information System (PaGWIS) and other unpublished PaGS reports. Each well used in the analysis contains a measurement of the depth to bedrock (in feet) and/or a notation indicating if bedrock was encountered during well drilling, these attributes allow well records to be separated into two datasets – bedrock wells (wells that penetrate bedrock) and drift wells (wells that did not encounter bedrock).Topographic Position Index (TPI) is a quantitative landform analysis that uses land surface elevation data to determine landforms such as ridge, upper slope, middle/flat slope, lower slope, and valley. A composite TPI raster for each of Pennsylvania’s 23 physiographic sections was generated. Each well data point was attributed to a physiographic section and assigned a TPI value based on its location. The square root of depth-to-bedrock was calculated for each well. A linear regression relationship between the TPI and the square root of sediment thickness was established for five TPI classes (ridge, upper slope, middle/flat slope, lower slope, and valley) in each of the 23 physiographic sections. This statistical relationship was used to create a surrogate model for depth to bedrock to predict sediment thickness across the state. Synthetic data points were generated from the surrogate model to fill in areas of low well data density. A combination of bedrock well data points and synthetic data points were used to generate the first-iteration sediment thickness model through a natural neighbor interpolation technique. Iterative refinements to the sediment thickness model were made by comparing model predictions to drift well data points. If the total depth of the drift well was less than the predicted thickness of sediment at that location, then the drift well data point was ignored. If the total depth of a drift well was greater than the predicted thickness of sediment at that location, then the drift well data point was added to dataset and a new sediment thickness model was generated. In total, 413, 474 data points were used in the modeling process – 207,130 empirically derived well points and 206, 344 synthetic points derived from the surrogate model.The final sediment thickness model was resampled to a 100-meter grid digital raster conforming to a similar resolution surface topography digital elevation raster. The surface topography grid was smoothed to remove detail before subtracting the sediment thickness to create a bedrock elevation map. The degree of smoothing was applied proportionally to the magnitude of sediment thickness. Portions of the surface topography grid that correspond to sediment thickness greater than 365 feet received the maximum amount of smoothing; likewise, portions of the surface topography grid that correspond to zero sediment thickness received no smoothing. The remaining portions of the surface topography grid that correspond to sediment thickness between 0 and 365 feet received gradational smoothing proportional to the sediment thickness.This 100-meter grid bedrock elevation raster was calculated by subtracting the sediment thickness model from the conditionally-smoothed surface topography digital elevation raster.
Purpose:
Bedrock surface topography digital elevation raster of Pennsylvania prepared at a 100 meter grid cell size to be used as a predictor of bedrock elevation for mapping and/or decision making. Bedrock elevations presented within the integer raster values are relative to the North American Vertical Datum of 1988 (NAVD88) in feet. The elevation data is presented as a 3-band raster in feet above mean sea level. Each cell contains three values: a predicted bedrock elevation and the upper and lower bounds of the prediction.
Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date:20230302
Currentness_Reference:
Commonwealth of Pennsylvania
Status:
Progress:Complete
Maintenance_and_Update_Frequency:As needed
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate:-80.617872
East_Bounding_Coordinate:-74.615853
North_Bounding_Coordinate:42.283011
South_Bounding_Coordinate:39.673484
Keywords:
Theme:
Theme_Keyword_Thesaurus:ISO 19115 Topic Categories
Theme_Keyword:elevation
Theme_Keyword:environment
Theme_Keyword:geoscientificInformation
Theme:
Theme_Keyword_Thesaurus:None
Theme_Keyword:DEM
Theme_Keyword:Bedrock
Theme_Keyword:Bedrock Geology
Theme_Keyword:Geology
Theme_Keyword:Pennsylvania
Theme_Keyword:Elevation
Theme_Keyword:PAGS
Theme_Keyword:Pennsylvania Geological Survey
Theme_Keyword:DCNR
Theme_Keyword:Department of Conservation and Natural Resources
Access_Constraints:None
Use_Constraints:
The data contained in the geodatabase may be used provided that credit for the original (unaltered) data is given to the Pennsylvania Bureau of Geological Survey, Department of Conservation and Natural Resources. Users shall clearly indicate the source of the data. Users who modify the data in any way are obligated to describe the types of modifications they have made. Users are not to misrepresent these Pennsylvania Bureau of Geological Survey (or PaGS) data, nor to imply that changes they (users) have made were approved by the PaGS.These data are public information and, as such, the data may be used as a reference source and may be interpreted by organizations, agencies, units of government, or others based on needs; however, each user is responsible for the appropriate application of the data. Federal, state, or local regulatory bodies are not to reassign to PaGS any authority for the decisions they make using these data.The data are not meant for site-specific analysis at scales finer (i.e., larger, more detailed) than 1:24,000. Users are not to misrepresent the data by presenting any at scales for which it is not intended, nor to imply that presentation at such scales is approved by the PaGS.Not for commercial resale.Distribution LiabilityThese data files and accompanying documentation are provided "as is," and the user assumes the entire risk as to their quality and performance.The Commonwealth of Pennsylvania makes no guarantee or warranty concerning the accuracy of information contained in the geographic data or accompanying documentation. The Commonwealth of Pennsylvania further makes no warranties, either expressed or implied, as to any other matter whatsoever, including, without limitation, the completeness or condition of the product, or its fitness for any particular purpose. The burden for determining fitness for use lies entirely with the user.Although these data have been processed successfully on a computer system at the Department of Conservation and Natural Resources, the Commonwealth of Pennsylvania makes no warranty, expressed or implied, regarding the use of the data files or accompanying documentation on any other computer system, nor does the act of distribution constitute any such warranty.Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the Commonwealth of Pennsylvania government or any agency thereof.The user shall save the Commonwealth of Pennsylvania harmless and indemnify it from any suits, claims, or actions arising out of the use of or any defect in the data files or accompanying documentation. The Commonwealth of Pennsylvania assumes no legal liability for the accuracy, completeness, or usefulness of the data files and accompanying documentation. In no event shall the Commonwealth of Pennsylvania have any liability whatsoever for payment of any consequential, incidental, indirect, special, or tort damages of any kind, including, but not limited to, any loss of profits arising out of use of or reliance on the geographic data.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:Pennsylvania Department of Conservation and Natural Resources
Contact_Person:Pennsylvania Geological Survey
Data_Set_Credit:
Pennsylvania Geological Survey, 2023
Native_Data_Set_Environment:
Version 6.2 (Build 9200) ; Esri ArcGIS 10.8.1.14362
Back to Top
Data_Quality_Information:
Lineage:
Source_Information:
Type_of_Source_Media:onLine
Source_Contribution:
Well records assembled from published records from Pennsylvania GroundWater Information System (PAGWIS) and unpublished borehole data from the glaciated portion of northwestern Pennsylvania.

PAGWIS Database
Pennsylvania Geological Survey, 2022, PAGWIS - Pennsylvania groundwater information system: Pennsylvania Geological Survey, 4th ser., database. [Data accessed from http://gis.dcnr.pa.gov/pagwode/ in 2022.
Source_Information:
Type_of_Source_Media:None
Source_Contribution:
Surface topography digital elevation raster derived from lidar elevation data collected for the Pennsylvania Geological Survey PAMAP program in 2008 and distributed through PASDA at https://www.pasda.psu.edu.
Back to Top
Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method:Raster
Raster_Object_Information:
Raster_Object_Type:Pixel
Row_Count:2918
Column_Count:5079
Back to Top
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Map_Projection:
Lambert_Conformal_Conic:
Standard_Parallel:40.25
Standard_Parallel:41.5
Longitude_of_Central_Meridian:-78.0
Latitude_of_Projection_Origin:39.0
False_Easting:0.0
False_Northing:0.0
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method:coordinate pair
Coordinate_Representation:
Abscissa_Resolution:0.000000026869262370610162
Ordinate_Resolution:0.000000026869262370610162
Planar_Distance_Units:foot_us
Geodetic_Model:
Horizontal_Datum_Name:D North American 1983
Ellipsoid_Name:GRS 1980
Semi-major_Axis:6378137.0
Denominator_of_Flattening_Ratio:298.257222101
Back to Top
Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:Pennsylvania Spatial Data Access (PASDA)
Contact_Address:
Address_Type:mailing and physical address
Address:
115 Land and Water building
City:University Park
State_or_Province:Pennsylvania
Postal_Code:16803
Country:United States
Contact_Voice_Telephone:(814) 865 - 8792
Contact_Electronic_Mail_Address:pasda@psu.edu
Distribution_Liability:
 The USER shall indemnify, save harmless, and, if requested, defend those parties involved with the development and distribution of this data, their officers, agents, and employees from and against any suits, claims, or actions for injury, death, or property damage arising out of the use of or any defect in the FILES or any accompanying documentation. Those parties involved with the development and distribution excluded any and all implied warranties, including warranties or merchantability and fitness for a particular purpose and makes no warranty or representation, either express or implied, with respect to the FILES or accompanying documentation, including its quality, performance, merchantability, or fitness for a particular purpose. The FILES and documentation are provided "as is" and the USER assumes the entire risk as to its quality and performance. Those parties involved with the development and distribution of this data will not be liable for any direct, indirect, special, incidental, or consequential damages arising out of the use or inability to use the FILES or any accompanying documentation.
Back to Top
Metadata_Reference_Information:
Metadata_Date:20230601
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:Pennsylvania Department of Conservation and Natural Resources
Contact_Person:Pennsylvania Geological Survey
Contact_Address:
Address_Type:physical
Address:
3240 Schoolhouse Road 
City:Middletown
State_or_Province:PA
Postal_Code:17057-3534
Contact_Voice_Telephone:717-702-2017
Metadata_Standard_Name:FGDC Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version:FGDC-STD-001-1998
Metadata_Time_Convention:local time
Back to Top