Memorandums made in Ireland in the autumn of 1852 . angement of the rocks variesconsiderably in different places. For instance, thelias and greensand are often wanting, and the chalkis then found resting on the sandstone or some rockstill lower; while, on the other hand, the chalk isoften absent, at least partially, as in the GiantsCauseway cliffs, the trap rocks there lying imme-diately on the ochrey and greensand beds. Evenwhen the chalk is present, the basaltic rocks seldomrest directly on it, an ochreous conglomerate, mixed THE GIANTS CAUSEWAY. 163 with clay, being usually interposed. The
Memorandums made in Ireland in the autumn of 1852 . angement of the rocks variesconsiderably in different places. For instance, thelias and greensand are often wanting, and the chalkis then found resting on the sandstone or some rockstill lower; while, on the other hand, the chalk isoften absent, at least partially, as in the GiantsCauseway cliffs, the trap rocks there lying imme-diately on the ochrey and greensand beds. Evenwhen the chalk is present, the basaltic rocks seldomrest directly on it, an ochreous conglomerate, mixed THE GIANTS CAUSEWAY. 163 with clay, being usually interposed. The lowerpart of the trap series, next the chalk, consistschiefly of amygdaloid, intermingled with green-stone, tabular basalt, and thin courses of red middle region is occupied by great beds ofcolumnar basalt and red ochre, while the upperportion consists chiefly of coarse crystalline green-stone/ The annexed section, taken from Mr. BrycesMemoir, shows the position and relations of thesix great beds in the cliffs east of the //. Several beds of basalt, ochre, and green-stone. C e. Upper bed or range of columnar basalt, 54feet. d, d. Bed of irregular prismatic basalt, 54 feet. C c. First bed or range of columnar basalt, 45feet. \/A^i^yJt>y^ ^^Vi\ O _. The great oclire bed, from 20 to 25 =. rEjFidE——^T^hM °~ Amygdaloid, with greenstone and thin-=EL\ courses of red and speckled ochre. 160 feet — ==1 thick, as seen above water in Pleaskin. g. Sea-line. k. Sandstone under water, not seen. These beds (//) form the top of the cliffs and 164 DESCRIPTION OF grassy knolls rising behind. When complete, asthey are in the eastern cliffs towards Portmoon,they are 150 feet thick. Keeping in view this arrangement of the strata,as holding good over all the causeway district, itbecomes easy to understand the relation of theGiants Causeway proper to the neighbouring cliffs,and how it has come to occupy its present positionand to exhibit its present aspect.
Size: 1095px × 2281px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1850, bookidmemorandumsm, bookyear1853
