Ruskin — Banded and Brecciated Concretions, 



209 



pale brown agatescent jasper in multitudinous concretions, plainly- 

 visible on the surface, like the convolutions of the brain of an 

 animal. But in the typical examples of the whole series, no lines of 

 concretion are visible on the surface ; it is knotted and pitted ; but 

 not banded — it is of grey clear chalcedony, and the entire mass of 

 the stone is often thrown into irregularly contorted folds, which are 

 sometimes parallel to tlie interior bands, and from which I shall, 

 for convenience sake, give the name to the whole group of " Folded 

 Agates." 



I say '' sometimes parallel," because the folds of the interior beds 

 are much more complex than those of the surface, and often are 

 most notable when the exterior is undisturbed ; and they are 

 specifically peculiar in two respects. First, they are formed out of 

 beds which are in the greater part of their course accurately 

 parallel, and arranged in gracefully sweeping continuous curves, 

 while the bands of ordinary agates are broken into minor undulation, 

 and run into irregular curves. Fig. 1 is the typical structure of 

 common, and Fig. 2 of folded agate ; the line a h, in each figure, re- 

 presenting the surface of the stone. 



Fig. 1. 



Secondly, These sweeping and beautifully parallel beds are at par- 

 ticular points of their course suddenly and systematically contracted, 

 and bent outwards, (outwards, that is to say, in nested agates — in- 

 wards in stellar agates, but the stellar formation is very rare in this 

 group) like flowing drapery raised by a rod beneath it ; and this ideal 

 rod may either raise these sheets of drapery hanging over it, as clothes 

 hang over a line ; or on the end of it, as the sides of a tent hang from 

 its pole ; ^ with every variety of beautiful curvature, intermediate be- 

 tween these two arrangements. The ideal rod is of course composed 

 of the interior chalcedony or quartz ; and I once supposed the entire 

 range of these phenomena to be dependent on the former subtle 

 influx of the dissolved silica at the points where the apparent rods 

 or tubes reached the exterior of the stone ; but I now believe rather 



^ In Plate XIII. Fig. 1 shows the clothes-line arrangement in pure surface-section, 

 and Fig. 2 in perspective, seen through the transparent stone, the edges only of the 

 pendant veils being at the surface. Of the tented arrangement I will give examples 

 In succeeding plates, but they are not specifically different arrangements ; they are 

 only accidental variations in the direction of the interrupting masses. 



