1013 



GIBBON. 



GINSENG. 



1014 



the uppermost of which is perhaps traceable in the cliffs of the Cave- 

 Hill over Belfast, and is distinctly observable at Fairhead, on the 

 north-eastern extremity of the coast, where the mural precipice of 

 greenstone is articulated into columns of enormous dimensions but 

 rude structure, some of them measuring 250 feet in length by 6 feet 

 on the side. The same formation appears occasionally to recur 

 along the verge of the precipice which trends westward hence to 

 Dunaeverick, at a short distance from which the two lower beds 

 emerge from the sea, and, rising along the escarpment of the rock, 

 form colonnades of the most striking appearance for a distance of 

 nearly three miles, when the upper one is lost in the surrounding 

 masses of basalt, while the lower stratum sinks again under water, 

 its denuded extremity forming that particular group of columns 

 known as the Giants' Causeway. 



A section of the cliff at Bengore-Head, immediately adjoining the 

 Causeway, gives the following arrangement : 



Feet. 



1. Basalt, rudely columnar 60 



2. Red Ochre, or Bole 9 



3. Basalt, irregularly prismatic 60 



4. Columnar Basalt 7 



5. Intermediate, between Bole and Basalt 8 



6. Coarsely Columnar Basalt 10 



7. Columnar Basalt, the upper range of pillars at Bengore-Head 54 



8. Irregular Prismatic Basalt. In this bed the wacke and wood 



coal of Port Noffer are situated 54 



9. Columnar Basalt, the stratum which forms the Causeway by 



its intersection with the plane of the sea . . . .44 



10. Bole, or Red Ochre 22 



11, 12, 13. Tabular Basalt, divided by seams of Bole . . .80 

 14, 15, 16. Tabular Basalt, occasionally containing Zeolite . . 80 



488 



It is observable that the dimensions of the columns dimmish and 

 the perfection of their structure increases as the strata descend. Thus 

 the most perfect arrangement is found in the lowest stratum, of 

 which arrangement the Causeway affords the most perfect specimen. 

 The upper part of the stratum being here denuded for a distance of 

 about 300 yards, exhibits an irregular pavement formed of the tops 

 of polygonal columns, so closely arranged that the blade of a knife 

 can with difficulty be inserted in the interstices. The columns are 

 chiefly hexagonal, but polygons of five, seven, and eight sides are of 

 frequent occurrence ; and there is one instance of a triangular prism. 

 These columns are divided into joints of unequal length ; each joint 

 is formed by the adjacent extremities being relatively convex and 

 concave, an arrangement which is further secured by the overlapping 

 of the external angles. These convexities and concavities are seg- 

 ments of spheres, the base of each of which occupies a circle inscribed 

 in the polygon of the pillar ; the intervals intercepted between the 

 peripheries of these circles and the sides of the polygon are all in the 

 plane perpendicular to the axis of the column. The stone is the 

 most compact and homogeneous variety of basalt, and is more or less 

 sonorous when struck with a hard substance. The entire mass of 

 these columns, of which about thirty feet are exposed above the 

 surrounding shingle at the highest point of their denudation, bears 

 a strong resemblance to an artificial mole projecting from the base of 

 the cliff into the sea. 



It is probable that the columnar beds of which the exposed edges 

 present these remarkable appearances along the coast underlie the 

 cupping of tabular basalt to a considerable distance inland, as columnar 

 facades break out on the seaward slope of the entire line of elevations 

 extending from Ballycastle to Bushmills, and indications of a columnar 

 tendency have been observed in beds of tabular basalt as far inland as 

 fikn Rovel, near Cushindall, and at the Cave-Hill, near Belfast. Along 

 the coast at Ushethaven, Roanscarave, and Thivigh, are several 

 smaller causeways nearly as perfect as the one described. The colum- 

 nar strata of the islands of Rathlin and Staffa indicate the extent of 

 the same formation northward and eastward. 



The vicinity of the Giants' Causeway affords numerous appearances 

 confirmatory of the opinion that the basalt when superinduced over 

 the secondary strata was in a state of fusion from heat : such are 

 the conversion of old red-sandstone into horustone, the conversion of 

 clay -slate into flinty-slate, the conversion of coal into cinders, and in 

 numerous instances the conversion of chalk into granular marble, all 

 arising from the contact of trap dykes with the altered strata. At 

 Kenbaan, near Ballintoy, the basalt is found inclosing detached masses 

 of chalk, as well interspersed through trap dykes as in the mass of 

 the formation. Similar instances occur near the Cave-Hill. 



Although this is the most important trap district in Ireland, yet 

 basaltic formations are not altogether peculiar to it, columnar facades 

 having been observed in the county of Limerick. [BASALT.] 



(Philotopkical Traruactiow ; Traneactions of the Geological Society, 

 vol. iii. ; Guide to the Giant j (JavMway, Dublin.) 



GIBBON. [HTLOBATES.] 



GIBBSITE, a Mineral consisting of a hydrate of alumina. It 

 occurs in small stalactitic shapes, or marntnillary, and iucrusting. 

 The colour is grayish or greenish-white. The surface is smooth but 

 nearly dull. Structure sometimes nearly fibrous. Its hardness is 3 



to 3-5. Specific gravity 2'3 to 2'4. It occurs in a bed of iron ore at 

 Richmond in the United States of America. This mineral results 

 from the decomposition of felspar, and consists of little else besides 

 water and alumina. 



GIESECKITE, a form of Elceolite from Greenland. [EL.sor.iTE.] 

 GIGANTHOLITE, a Mineral which occurs crystallised in six- and 

 twelve-sided prisms. Its cleavage is parallel to the six sides of the 

 prism. Colour greenish to dark steel-gray. Lustre between vitreous 

 and waxy. Hardness about 3'5. Specific gravity 2-862 to 2'878. It 

 is found near Temmela in Finland. The following is its analysis by 

 Wachtmeister : 



Silica .... 



Alumina 



Peroxide of Iron 



Magnesia 



Protoxide of Manganese 



Potash . 



Soda .... 



Fluorine, a trace 



Water with Ammonia 



46-27 

 25-10 

 15-60 



3-80 



0-89 



2-70 



1-20 



6-00 

 . 101-56 



GILBERTITE, a Mineral occurring in plates lying irregularly 

 together. Its colour is white with a shade of yellow. Hardness 275. 

 Lustre silky. Translucent. Specific gravity 2'648. It is found near 

 St. Austell, Cornwall. The following is its analysis by Lehunt : 



Silica 

 Alumina 

 Lime . 

 Magnesia 

 Protoxide of Iron 

 Water . 



45-155 

 40-110 



4-170 



1.900 



2-430 



4-250 



-98-015 



GILBERTSOCRINUS, a genus of fossil EcUnida, from the Moun- 

 tain Limestone. (Phillips.) 



GILL-COVERS. [FisH.] 



GILLENIA, a genus of Plants belonging to the natural order 

 Rosacea, and the sub-order Spirew. It has a tubularly campanulate 

 5-cleft calyx, 5 linear lanceolate petals, 10-20 stamens, very short, 

 inclosed in the tube, 5 carpels almost united into a five-celled capsule, 

 and 2 seeds in each cell. There are only two species of this 

 genus. 



0. trifoliaia has several stems from the same root, a foot or two in 

 height, alternate trifoliate leaves, the flowers, which are few in 

 number, forming a sort of panicle. The calyx sub-campanulate, or 

 tubular, with the lower half narrowest, the border divided into 5 

 reflexed acute teeth. Petals 5, the two upper ones separated from the 

 three lower ones, white with a reddish tinge on the edge, lanceolate, 

 unguiculate, contracted, and approximated at the base. The stamens 

 about 20, in a double series within the calyx. Capsules 5, diverging, 

 oblong, acuminate, 2-valved, 1- or 2-seeded. It is a native of North 

 America in shady places, from Florida to Canada. The root is 

 emetic, and possesses properties similar to those of ipecacuanha. It 

 must however be administered in larger doses, and is not so certain 

 in its effects. Some authors attribute a tonic power to this plant 

 when taken in small doses. 



0. stipulated is distinguished by its foliaceous ovate deeply-cut 

 stipules. It grows in humid woods and damp places from Tennessee 

 to Kentucky, in North America. The medicinal properties of this 

 species are the same as those of 0. trifoliata. 



The species of GUlenia are elegant and hardy plants, and are 

 therefore worthy of cultivation. They grow best in a peat soil, 

 and may be readily propagated by dividing at the roots early in 

 the spring. 



(Don, Dichlamydeous Plant! ; Lindley, Flora, Sfedica.) 



GILLIESIA'CE^E, Gillexiadt, a very singular natural order of 

 Endogens, with the habit of the Scilleous division of Liliaceas, but 

 with extremely remarkable flowers. In the first place there are 

 several bracts at the base of each flower, resembling a calyx, and in 

 reality constituting an involucre ; and secondly the calyx is either an 

 urceolate 6-toothed body, or a single lobe resembling a labellum. 

 Of the two known genera, Gillesia and Miersia, one has six perfect 

 stamens, the other has only three perfect and the remainder sterile 

 and nearly obliterated. They are natives of Chili. ('Botanical 

 Register,' folio 992.) 



GILLS. [FiSH.] 



GILLYFLOWERS, the common name of the Garden Stock, Mat- 

 thiola incana. [MATTHIOLA.] 



GILT-HEAD. [CHRYSOPHRYS; CBENILABHUB.] 



GINGER. [ZlNGIBEH.] 



GINSENG, a root found in China, to which extraordinary pro- 

 perties have been ascribed : it is not only considered a universal 

 remedy for all maladies, but is spoken of in the highest terms as a 

 specific in particular circumstances. Volumes have been written in 

 Chinese upon the supposed virtues of this root. It is affirmed that it 

 wards off fatigue, invigorates the enfeebled frame, restores the 

 exhausted animal powers, makes old people young, and BO on. Tha 



