WATSON — NOTES ON JIETALLIFEROUS SADDLES. 
3G1 
might have been, continued to act from tlic right on the lower por- 
tion of the already contorted beds. 
In the shale beds these rapid contortions do not strike us with so 
much surprise as when the phenomena is seen in the more massive 
and coherent beds of limestone ; and then it seems scarcely credible, 
even to the geologist, that the folded strata could ever have been de- 
posited horizontally, and that, with comparatively so little fracture, 
they could have been bent into their present form by simple pressure. 
In cases where a separate well marked bed, left standing, forms the 
roof and sides of a level in a mine, the entrance to such level from a 
transverse gallery or shaft wears all the appearance of an arch of 
artificial masonry, and the deception is only removed by close 
inspection of the contiguous rock. Natural arches, formed by the 
weathering and removal of the soft beds, are not uncommon in cliff 
sections of contorted rocks, but then the spread of the strata is 
iisually much wider, and the idea of such vast compressing force 
having been put in action is not so obtruding. The coal-measure 
" binds" (argillaceous sandstones) on the shores of Carmarthen Bay 
between Saundersfoot and Tenby display some very remarkable ex- 
amples of weathered contorted beds, but they are in no respects 
equally striking with those of the limestone strata above described. 
Next to the form and structure of the saddles we may conveniently 
consider the associated minerals ; but, before we can do this satis- 
factorily, the circumstances connected with theii' union with the 
metallic veins — which invariably, in the districts which now occupy 
us, form part of the general sj' stem of displacements of the stratifica- 
tion — must have our attention ; and perhaps it may simplify matters 
in this respect if we select an example for description. Let us take 
the case of the Old Ecton mine, in the parish of Alstonfields, North 
Staffordshii'e. This mine deserves our choice not only because it has 
made very large returns of ore, but also because, from the length of 
time it has been working, the ground has been so thoroughly opened 
that the relationship between the saddles and veins has been better 
made out than in more recently opened and less developed setts in 
that neighbourhood. The veins which here exist are " pipe veias" 
and "rake veins," and may be thus particularized. 
The pipe veins are iri'egular cavities inclined at angles varying from 
fifteen to thirty-five degrees to the horizon; have no proper longitu- 
dinal bearing, like the Cornish lodes for instance ; and have generally 
the most important of their expansions parallel to the bedding of the 
strata wdiich they traverse ; and whose dip is also the direction of 
the pipes, although these are by no means always confined to any 
distinct bed of stone, but, on the contrary, usually pass through 
several beds in succession until they reach the saddles. The general 
relations of a pipe vein to the stratification of the rocks is shown in 
fig. 3, E E, which also represents the course of such a vein through 
the different beds in the direction of their dip, as jiist mentioned. 
The rake veins in the Ecton district are usually a series of vertical 
fissures falling in with the pipe veins, and, occasionally, passing 
VOL. III. 2 z 
