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 did not legally belong to the house of Habsburg until 1453, when Duke Ernest’s son, the emperor Frederick III. (Frederick V., duke of Styria and Carinthia, 1424–1493, of Austria, 1463–1493), confirmed the privilegium maius and conferred the title of archduke of Austria on his son Maximilian and his heirs. The title archduke (or archduchess) is now borne by all members of the Austrian imperial house.

See John Selden, Titles of Honor (1672); Antonius Matthaeus, De nobilititate, de principibus, deducibus, &c., libri quatuor (Amsterdam and Leiden, 1696, lib. i. cap. 6); Pfeffel, Abrégé chronologique de l’hist, el du droit public d’Allemagne (Paris, 1766); Brinckmeier, Glossarium diplomaticum, &c. (1850–1863, 2 vols.); J. F. Joachim, “Abhandlung von dem Titel ‘Erzherzog,’ welchen das Haus Oesterreich führt.” in Prüfende Gesellschaft zu Halle, 7; F. Wachter, art. “Erzherzog,” in ''Allgem. Encykl. der Wissenschaften u. Künste (1842, pub. by Ersch and Gruber); A. Huber, Ueber die Entstehungszeit der oesterreichischen Freiheitsbriefe (Vienna, 1860); W. Erben, Das Privilegium Friedrichs I. für das Herzogtum Österreich'' (Vienna, 1902).

ARCHEAN SYSTEM (from , beginning), in geology. Below the lowest distinctly fossiliferous strata, that is, below those Cambrian rocks which bear the Olenellus fauna, there lies a great mass of stratified, metamorphic and igneous rock, to which the non-committal epithet “pre-Cambrian” is often applied; and indeed in not a few instances this general term is sufficiently precise for the present state of our knowledge. Nevertheless there are large tracts, both in the Old World and in the New, in which a subdivision of this assemblage of ancient rocks is not only possible but desirable. It is quite clear in certain regions that there is a lowermost group with a prevailing granitoid, gneissic and schistose facies, mainly of igneous origin, above which there are one or several groups bearing a distinctly sedimentary aspect. It is to this lowermost gneissic group that the term “Archean” may be conveniently limited.



Thus, while the name “pre-Cambrian” may be used to indicate all these very old rocks whenever there is still any difficulty in subdividing them further, it is an advantage to have a special appellation for the oldest group where this can be distinguished.

It must be pointed out that the term “Archean” has been used as a synonym for pre-Cambrian; and that the expressions Azoic (from -, privative; , life), Eozoic (from  , dawn), and Fundamental Complex, have been employed in somewhat the same sense. Archeozoic has been proposed by American writers to apply to the lowest pre-Cambrian rocks with the same significance as “Archean” in the restricted sense employed here; but it is perhaps safer to avoid any reference to the supposed stage of life development where all direct evidence is non-existent. The so-called “Azoic” rocks have already been made to yield evidence of life, and there is no reason to presuppose the impossibility of finding other records of still earlier organisms.

The prevailing rocks of the Archean system are igneous, with metamorphosed varieties of the same; sedimentary rocks, distinctly recognizable as such, are scarce, though highly metamorphosed rocks supposed to be sediments, in some regions, take an important place.

There are several features which are peculiarly characteristic of the Archean rocks:—(1) the extraordinary complexity of the assemblage of igneous materials; (2) the extreme metamorphism and deformation which nearly all the rocks have suffered; and (3) the inextricable intermixture of igneous rocks with those for which a sedimentary origin is postulated. Wherever the Archean rocks have been closely examined two great groups of rocks are distinguishable, an older, schistose group and a younger, granitoid and gneissic group. For many years the latter was supposed to be the older, hence the epithets “primitive” or “fundamental” were applied to it. Now, however, it has been shown, both in Europe and in North America, that in certain regions a schistose series is penetrated by a gneissose series and when this occurs the schists must be the older. But bearing in mind the difficulties of interpretation, it is not at all unreasonable to assume that there may yet be regions where the gneissose rocks are the oldest; for where no schistose series is present there may be no criterion for estimating the age of the granites and gneisses. The exceedingly great difficulties which lie in the way of every attempt to unravel the history of an Archean rock-complex cannot be too forcibly emphasized; for to be able to demonstrate the order of events and succession of rocks we should at least know whether we are dealing with sediments, flows of volcanic material, or intrusions, yet in many instances this cannot be done. In some areas the gradual passage of highly foliated and metamorphosed schists may be traced into comparatively unaltered arkoses, greywackes, conglomerates; or into volcanic lava-flows, pyro-clastic rocks or dikes; or again through a gneissose rock into a granite or a gabbro; but the districts wherein these relationships have been thoroughly worked out are very few.

This much may be said, that where the Archean system has been most carefully studied, there appears to be (1) a schistose series, of itself by no means simple but containing the foliated equivalents of sedimentary and igneous rocks; into this series a gneissose group (2) has been intruded in the form of batholites, great sheets and sills with accompanying intrusional prolongations into the schists; subsequently, into the gneisses and schists, after they had been further deformed, sheared and foliated, another set (3) of dikes or thin sheet-like intrusions penetrated. All this, namely, the formation of sediments, the outpouring of volcanic rocks, their repeated deformation by powerful dynamic agencies and then their penetration by dikes and sheets had been completed and erosion had been at work upon the hardened and exposed rocks, before the earliest pre-Cambrian sediment was deposited.

There has been much premature speculation as to the nature and origin of these very ancient rocks. The prevalence of regular foliation with layers of different mineral composition, producing a close resemblance to bedding, has led some to imagine that the gneisses and schists were themselves the product of the primeval oceans, a supposition that is no longer worthy of further discussion. Others have supposed that the gneisses were largely produced by the resorption and fusion of older sediments in the molten interior of the earth; there is no evidence that this has taken place upon an extended scale, though there is reason to believe that something of this kind has happened in places, and there is in the hypothesis nothing radically untenable. In one way the sedimentary schists have undoubtedly been incorporated within the gneissose mass, namely, by the extremely thorough and intimate penetration of the former by the latter along planes of foliation; and when a complex mass such as this has been further sheared and metamorphosed, a uniform gneiss appears to result from the intermixture.

A not uncommon cause of the apparently bedded arrangement of layers of different mineralogical composition may be traced to the original differentiation of the granitoid magma into different mineral-sheets. When these mineralogically