“Yes, that must be the extension of the Aurora lead. And if I am not mistaken this ridge is a wedge of porphyry, what geologists call a dyke, thrust up between these two veins. Probably it narrows in or pinches, as they say, just here, and further on would thicken again.”
“Do you mean that it split what was originally one vein,” Len asked, “and pried the halves apart?”
“No, I should say not, for, as you know, the rock in the Last Chance is different from that in the Aurora. Probably the dyke was formed first, and the lodes came afterward by forcing themselves between it and the trachyte-body of the mountain.”
“That’s a’ vera interesting,” was Sandy’s dry remark, “but, in my eegnorance, permeet me to ask how it affects our eenterests practically? A blind man’s nae judge o’ colors, ye ken.”
“I am not sure that it affects our interests at all, and yet I have an idea it may.”
“Trot out your little idea!” exclaimed Len, with characteristic impatience; and with equally characteristic caution Max declined to do so until he had thought more about it. Whereupon, with good-natured compliance, his questioners departed and busied themselves in hunting for more of the tart berries of the Oregon grape, which grew purple among the lichen-printed stones.
Returning half an hour later they found Max pacing slowly down the crest of the ridge like a sentinel on a rampart.
“I want you fellows to help me get the breadth or thickness of this dyke here as nearly as we can come at it.”
“Oh, by pacing over the ridge and estimating it carefully.”