Tutorial
From www.archaeogeophysics.org
This page will provide step by step instructions on how to operate geophysical instruments in the field as well as how to process data generated in the field. Each page will generally focus on individual tasks.
Contents |
Pre-Test
A basic exam to cover your general knowledge of geophysics. Take exam first to evaluate what you know and then afterwards to see what you have learned.
Ground-Penetrating Radar
One of the most promising of geophysical methods for rapid terrain characterization at depth is ground-penetrating radar (GPR). In this method microwaves are transmitted through the ground and the time of reflection and intensity is measured. Differences in the composition of subsurface materials can be measured as a function of the reflected energy. These data may be converted into depth/x-y location as needed with relative ease. Such an instrument may be towed at rates of up to 10 miles an hour, making GPR an immediately practical large area tool.
Magnetometry
This page provides steps for setting up and using the Geometrics 858 Cesium Vapor Magnetometer. This is the particular instrument used by the by the faculty and students of CSULB’s archaeology program.
Resistivity
A capacitively coupled resistivity meter measures the electrical properties of rocks and soil without cumbersome ground stakes used in traditional resistivity surveys. A simple coaxial-cable array with transmitter and receiver sections is pulled along the ground either by a single person or attached to an all-terrain vehicle. Data collection is many times faster than systems using conventional DC resistivity.
Conductivity
Conductivity measures the ease of electric current flow as it moves through the subsurface. It is the inverse of resistivity, but unlike resistivity, conductivity does not require actual electrical contact to induce the flow of a current into the ground. Conductivity is an appropriate method when an electrical contrast within the soil matrix is expected.
Global Positioning System (GPS)
Use of a Global Positioning System when collecting geophysical data is vital; especially when you are integrating your data into GIS. It is important to record the corners of your survey grids in a GPS unit so that you may geo-rectify your processed data in the GIS software. Specific tasks such as geo-rectification will require their own web-pages that include step by step procedures .
Analysis and Integration
One of the most powerful and dynamic tools for interpreting processed geophysical data is GIS programs such as ArcGIS. Geophysical data may be integrated into GIS by directly importing processed data as image files or interpolating raw data within ArcGIS itself. Either way different datasets may be overlain on top of one another as layers. These layers may then be compared using statistical processes located in the programs toolbox. The website will include step by step instruction on ways to incorporate geophysical data into ArcGIS as well as various techniques for analyzing the data.
- Georectification in ArcMap
- Converting Rasterized Geophysical Data into Vectors in ArcGIS
- Analyzing Patterns in Geophysical Data using Spatial Statistics in ArcGIS
Photogrammetry
Post-Tutorial Exam
An exam designed to evaluate your general knowledge about archaeogeophysics after you have conducted these tutorials.