The overall prospecting effectiveness or power of any given method is made up of four component parts. Three of these tend to increase with successful use and the passage of time. These are (a), the operating effectiveness, which, referring to getting the data, is based on the cost of field operations in time and money; (b), the technical effectiveness, which, referring to the quality of the data, is measured by the magnitude of the observational errors; and, (c), the resolving effectiveness, which, referring to the interpretation of the data, is measured by the ability to translate the data into terms of economic significance. The fourth component tends to decrease with successful use and the passage of time, and is, (d), the finding effectiveness, which is determined by the ratio of the magnitudes of findable anomalies to the magnitudes of the current observational errors. At any given time, the overall prospecting effectiveness of a given method is determined by that particular component which displays the minimum effectiveness.In the major petroleum producing provinces of the U.S.A., negligible or decreasing structure finding effectiveness is displayed by all of the successfully used structural prospecting methods with one exception, the drill, the overall structural prospecting power of which is limited by a low operating effectiveness. However, these methods with existing low structural finding powers, surface geology, gravity methods, and seismic methods, display a more than appreciable finding effectiveness for anomalies which cannot be readily interpreted in terms of structure. This situation indicates that the existing low overall efficacy of these various methods is determined not so much by a low absolute finding effectiveness as by a resolving power which is low because of structural inhibitions upon interpretation.The sedimentary hydrocarbon prospecting method was introduced upon a theoretical basis which involved the depth of the source and the postulate of local lateral homogeneity, but did not attain any measure of overall prospecting potency until its interpretation technique was relieved of such purely theoretical inhibitions. Subsequent development has shown that similar limitations upon refraction interpretation were responsible for the collapse of that method in 1930 after the method had displayed marked prospecting effectiveness for shallow high relief structure. Attention is called to the possibility that the removal of similar inhibitions also may result in a similar increase in resolving power for other methods which today display a low structure finding effectiveness, and thus lead to their renaissance because of their thereby increased overall prospecting effectiveness.