65'2 T. T. QUIRKE BOUDINAGE, AN UNUSUAL PHENOMENON 



were formed in the quartzite previous to deformation. However, in this 

 there is not complete agreement. Indeed, there are reasons for believing 

 that the qnartz veins were filled after the formation of the bondins. 



The quartz veins in neighboring bands of quartzite are not in linear 

 continuation. The size of veins is in relation to the thickness of the 

 quartzite bands, being narrow in thin bands and wide in thick bands. 

 The}^ show no appearance of having been bent or ruptured after filling. 

 They are typical fissure veins. The quartz veins appear to be thicker 

 near the center of the boudins than at the edges. They seem to be 

 lenticular, with their greatest thickness at the axis of the cylinders, ac- 

 cording to the indication on the figures (figures 2 and 4). The quartz 



Figure 3.- — BoucUnaf/e, Carricre de la CitadeUc. Bastac/ne, Belgium 



veins commonly are not truly lenticular. In many cases the vein is split 

 up into veinlets, but the total width of the veinlets along the central axis 

 is generally greater than the width of the veins at the edge of the boudins. 

 The position of these features in the major fold is in question, because 

 the general structure of the Bastogne area has not yet been determined. 



At the Carriere de la Citadelle the axis of boudinage appears to be 

 horizontal, but in another quarry, at Luzery, the boudins have a dip of 

 35 degrees southeastward. Lohest believes that they occur only on the 

 summits of folds, and it may be that the case at Luzery is on a roll near 

 the summit of the anticlinorium or at tlie top of an anticline plunging 

 at an angle of 35 degrees. 



However, in this particular place the veins are vertical, not noraial to 



