“It cannot be denied that the chemical-physical structure of the near surface layers of the earth's crust reflect their physical characteristics and chemical composition in the plant life that covers them, in spite of the many retractions and changes which the science of Botany has had to make in this matter. The fact that many plants and plant components can store up metals has been recognized and utilized by miners and geologists, in that they correlate the occurrence of certain trace elements such as gold and lead in certain plants with corresponding mineral deposits. On the other hand the science of Applied Geophysics has long sought a useful method for proving and possibly determining quantitatively the presence of hydrocarbons which have migrated through the overlying formations to the earth's surface. Hydrocarbons are found almost universally in the earth's crust near the surface layers usually irrespective of whether or not an appreciable deposit of oil exists in the vicinity. For example, methane is formed as the result of the decomposition of organic matter. Evidence of the actual effects of mineral deposits is therefore generally either obscured or cannot be proved.