The botany of Iceland (1912) (19782981624)

Title: The botany of Iceland
Identifier: botanyoficeland0101kold (find matches)
Year: 1912 (1910s)
Authors: Kolderup Rosenvinge, L. (Lauritz), 1858-1939; Warming, Eugenius, 1841-1924
Subjects: Botany -- Iceland
Publisher: Copenhagen, J. Frimodt
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library



Text Appearing Before Image:
214 THORODDSEN streams. The tuffs have usually a brownish-yellow colour owing to the intermixture of palagonite, a brown dully-lustrous alteration- product of tachylyte or basalt-glass, which constitutes the greater portion of the ground-mass of the rock; therefore the whole forma- tion is often called the palagonite formation. The tuffs consist of lava-dust and lava-fragments with an abundance of glass-pieces (pala- gonite, tachylyte), slag and bombs; loose anorthite-crystals are often abundant. The breccias are distinguished from the tuffs bv beins U %s
Text Appearing After Image:
Fig. 5. Cliffs 011 KlificS (tuff and breccia). The Veslmannaeyjar. more coarse-grained and containing larger, angular lava-pieces: the fragments consist of compact basalt, dolerile, pumice, slaggy lava and volcanic bombs: the separate fragments are often covered with a glassy crust. The palagonite formation is sometimes arranged in layers; sometimes not a trace of regular arrangement can be dis- cerned. The tuffs and breccias have been formed by volcanic erup- tions which chiefly ejected ashes and lava-fragments, and produced only a few lava-streams; the ruins of the numerous large volcanoes from which these eruptions proceeded may still be demonstrated. The palagonite formation is traversed by thousands of basalt dykes which branch and send out apophyses and intrusive sheets; very often the breccia and the tuff is filled with numerous hollow nodules and balls of basalt with a radiallv-columnar structure inside and