The Getchell veins are lenticular replacement bodies lying along arcuate branches of a complex range-front fault system. The fault zone cuts all rocks of the district and is tentatively dated as late Tertiary.

The more intensely mineralized portions of the deposit form a shallow blanket with roots that project downward into areas of sparse mineralization.    The gold shoots are restricted to areas of intense mineralization.

Native gold and native silver are the only economic minerals. The great bulk of the gold occurs in minute but microscopically visible particles. Some gold may also occur in submicroscopic particles and some may be in solid solution in pyrite and carbon.

The ore minerals, dissolved in alkali sulfide solutions, are believed to have been deposited when the sulfide ion concentration in the hydrothermal liquid decreased, making unstable the double sulfides of gold-, iron, and arsenic.

The Getchell deposit is similar in many ways to the Nevada quicksilver deposits and present-day hot-spring deposits. The Getchell ore occurrence may represent a gradation from the common epithermal gold deposit to the cinnabar deposit. It is therefore placed close to the feeblest end of the epithermal group.

For the purposes of this volume, the South Atlantic comprises the Atlantic Ocean south of a direct line from Tangier (Morocco) to the Guyana-Venezuela border and north of a direct line from Cape Town (South Africa) and Cape Horn (Argentina). At the end of 1997 this region contained 4.3% of the world's total discovered oil reserves and 2.4% of the world's total discovered gas reserves (Petroconsultants 1998).
On the basis of the 1997 figure, six countries - Brazil, Argentina, Nigeria, Gabon, Congo (Brazzaville) and Angola - host 96.3% of the region's oil reserves and 92.1% of the region's gas reserves. Figure 1 illustrates the geographical distribution of the reserve splits, Table 1 gives the details.<...>

The study of rocks and other mineral associations, especially of ore deposits, starts out from the purely descriptive. The composition of these materials, their geologic position in the most comprehensive sense, and their gross and fine structures and textures, etc., must be established. Further research must explain, first the "How"', then the "Why". The latter must comprise the interpretation of the association of materials and geologic position as well as each detail of texture and structure, even the smallest. On the knowledge obtained, one must build further and must generalize. Things of which the "Why" can be explained directly will serve in the explanation of others. In doing this the danger of circular reasoning will exist ; criticism is therefore invariably necessary, self-criticism most of all. The interpretations must, if possible, be reached along several paths, and the validity of the various paths must be carefully considered. <...>

There are about 4,600 species of animals today that are called mammals because, despite an astonishing diversity of form and habitat, they all share a long list of characters not found in any other organisms, such as the presence of mammary glands, the single bone in the lower jaw, and the neocortex of the forebrain. This makes them unambiguously distinct from their closest living relatives, and their unique characters together define a monophyletic taxon, the class Mammalia. Three subgroups are readily distinguished amongst the living mammals.