than excavation) is the goal for project preservation and compliance with applicable laws. The geophysical methods most commonly applied to archaeology are magnetometers, electrical resistance meters, ground-penetrating radar (GPR) and electromagnetic (EM) conductivity. These methods provide excellent resolution of many types of archaeological features, and are capable of high sample density surveys of very large areas and of operating under a wide range of conditions. While common metal detectors are geophysical sensors, they are not capable of generating high-resolution imagery. Other established and emerging technologies are also finding use in archaeological applications. Although geophysical surveying has been used in the past with intermittent success, good results are very likely when it is applied appropriately. It is most useful when it is used in a well-integrated research design where interpretations can be tested and refined. Interpretation requires a knowledge both of the archaeological record, and of the way it is expressed geophysically. Appropriate instrumentation, field survey design, and data processing are essential for success, and must be adapted to the unique geology and archaeological record of each site. In the field, control of data quality and spatial accuracy are critical to a successful mission completion. Analysis and evaluation The most important parts of the survey are analysis and evaluation. The types of questions that archaeologist often ask of survey data include: what is the evidence for first occupation of an area; when was this area occupied; how are sites distributed; where are sites located; what evidence is there for a settlement hierarchy; what sites are contemporary with each other; how has the modern landscape interfered with the visibility of archaeological remains; what sorts of activities can be recognized (e.g., dwellings, tombs, field systems); how many people lived in this area at any given time or how did population density change over time; why did people choose to live where they did; how has the landscape changed over time; what changes in settlement patterns have there been? However, answering such questions depends on the quality of the evidence, which is why it is important to evaluate the effectiveness and thoroughness of the survey or surveys that contribute that evidence. At times, one part of the survey may not have yielded the evidence one wanted to find. For instance, very little may have been found during a field walk, but there are strong indications from geophysical survey and local stories that there is