The tracheae are minute tubes exhibiting a faint transverse striation which is probably the indication of a spiral fibre.
Rocks scored by glacial ice and showing plain indications of striation, together with thousands of erratic blocks, are found scattered all over Iceland.
The steep icewalls at the margin of the inland ice show, especially where the motion of the ice is slow, a distinct striation, which indicates the strata of annual precipitation with the intervening thin seams of dust (Nordenskidld's kryokonite).
In the rapidly moving glaciers of the icefjords this striation is not distinctly visible, being evidently obliterated by the strong motion of the ice masses.
They occasionally exhibit striation and originate from large branched cells, the nucleus and unmodified part of which form conspicuous elements.
Roman glass beads are always drawn out, and nicked off hot, with striation Iengthways; except the large opaque variegated beads which are coiled.
Some of them are relics of the longitudinal moraines of the ice-sheet, and they run north-west to south-east, parallel to the striation of the rocks and to the countless parallel troughs excavated by the ice in the hard rocks in the same direction; while the Lojo As, which runs from HangOudd to Vesi-jarvi, and is continued farther east under the name of Salpausellia, parallel to the shore of the Gulf of Finland, are remainders of the frontal moraines, formed at a period when the ice-sheet remained for some time stationary during its retreat.
(X2000.) c.g, Chromatoid grains; v, vacuole; l.s, fold or striation.