"Ay, must we go?" cried Adan. "I could stand here till night, even
without dinner, my friends."

"I, too, am sorry," began Roldan. "But what is the matter?"

The great masses of cattle had begun to heave suddenly. They were
uttering hoarse growls of terror. The mustangs of the vaqueros stood
suddenly still, quivering. Then, abruptly, a horrible stillness fell.
All things breathing seemed to petrify. But only for numbered seconds.
From beneath came a low roar, gathering in volume like the progression
of a tidal wave; then the world heaved and rocked.

"Temblor! temblor!" went up as from one mighty horrified throat. The
priest shouted to the boys: "Stay where you are;" to Don Tiburcio and
his guests: "With all your speed after me."

They understood his meaning. The cattle were leaping over one another,
bellowing madly, giving no heed to the hoarse cries of the terrified
vaqueros. In a moment a blaze of colour was flying down the valley, a
long brown arm lifted high above it. In twenty seconds five thousand
tossing horns and blazing eyes and heaving flanks were in pursuit.

The vaqueros did their best, although their faces were white and their
lips shaking. Three that were between the uniting herds, had their legs
crushed into their mustangs' sides, and were borne along and aloft,
shrieking horribly, adding to the fury of the stampede. Another, trying
to head the cattle off, rode into a sudden split in the hard adobe soil
and went down beneath those iron feet.

The boys clung together. The wall was broad, but it rocked continuously,