Bulletin of the Geological Society of America . y^. Figure 4.—Boudinage, Bastogne, BelgiumTraced from photograph used In figure 8. Transverse lines are quartz veins. bands of quartzite, which arched both upward and downward into theless resistant ^^hyllites. The natural conclusion is that after compressionthe quartzite yielded to tension, giving rise to cracks which were dis-tributed equally throughout. The yielding to tension was more closelyspaced in the thin beds than in the thick beds. The actual openings appear to have been wider near the axes of thebeds than near the edges. The edges of
Bulletin of the Geological Society of America . y^. Figure 4.—Boudinage, Bastogne, BelgiumTraced from photograph used In figure 8. Transverse lines are quartz veins. bands of quartzite, which arched both upward and downward into theless resistant ^^hyllites. The natural conclusion is that after compressionthe quartzite yielded to tension, giving rise to cracks which were dis-tributed equally throughout. The yielding to tension was more closelyspaced in the thin beds than in the thick beds. The actual openings appear to have been wider near the axes of thebeds than near the edges. The edges of the boudins were folded themost. Apparently, the folded parts were straightened enough to take upthe slack, but the central parts, being unshortened originally, had tosupply means of expansion, and therefore cracked open instead. Thecentral part might have been compressed during the arching of the otherbeds, and therefore had a certain amount of elastic recovery. 654 T. T. QUIRKE BOUDINAGE, AX UNUSUAL PHENOMENON We may suppose, however, that the
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1890
