A double handful of tourists climbed down from the omnibus, chattering with excitement. From under the long brim of his cap, Radnal vez Krobir looked them over, comparing them with previous groups he’d led through Trench Park. About average, he decided: an old man spending money before he died; younger folks searching for adventure in an overcivilized world; a few who didn’t fit into an obvious category and might be artists, writers, researchers, or anything else under the sun.

He also looked over the women in the tour group with a different sort of curiosity. He was in the process of buying a bride from her father, but he hadn’t done it; legally and morally, he remained a free agent. Some of the women were worth looking over, too: a couple of tall, slim, dark Highheads from the eastern lands who stuck by each other, and another of Radnal’s own Strongbrow race, shorter, stockier, fairer, with deep-set light eyes under heavy brow ridges.

One of the Highhead girls gave him a dazzling smile. He smiled back as he walked toward the group, his wool robes flapping around him. “Hello, friends,” he called. “Do you all understand Tarteshan? Ah, good.”

Cameras clicked as he spoke. He was used to that; people from every tour group wasted pictures on him, though he wasn’t what they’d come to see. He went into his usual welcoming speech:

“On behalf of the Hereditary Tyranny of Tartesh and the staff of Trench Park, I’m pleased to welcome you here today. If you haven’t read my button, or if you just speak Tarteshan but don’t know our syllabary, my name is Radnal vez Krobir. I’m a field biologist with the park, doing a two-year stretch of guide duty.”

“Stretch?” said the woman who’d smiled at him. “You make it sound like a sentence in the mines.”

“I don’t mean it like that-quite.” He grinned his most disarming grin. Most of the tourists grinned back. A few stayed sober-faced, likely the ones who suspected the gibe was real and the grin put on. There was some truth in that. He knew it, but the tourists weren’t supposed to.

He went on, “In a bit, I’ll take you over to the donkeys for the trip down into the Trench itself. As you know, we try to keep our mechanical civilization out of the park so we can show you what all the Bottomlands were like not so long ago. You needn’t worry. The donkeys are very sure-footed. We haven’t lost one — or even a tourist — in years.” This time, some of the chuckles that came back were nervous. Probably only a couple of this lot had ever done anything so archaic as getting on the back of an animal. Too bad for the ones just thinking about that now. The rules were clearly stated. The pretty Highhead girls looked particularly upset. The placid donkeys worried them more than the wild beasts of the Trench.

“Let’s put off the evil moment as long as we can,” Radnal said. “Come under the colonnade for half a daytenth or so and we’ll talk about what makes Trench Park unique.”

The tour group followed him into the shade. Several people sighed in relief. Radnal had to work to keep his face straight. The Tarteshan sun was warm, but if they had trouble here, they’d cook down in the Trench. That was their lookout. If they got heatstroke, he’d set them right again. He’d done it before.

He pointed to the first illuminated map. “Twenty million years ago, as you’ll see, the Bottomlands didn’t exist. A long stretch of sea separated what’s now the southwest section of the Great Continent from the rest. Notice that what were then two lands’ masses first joined in the east, and a land bridge rose here.” He pointed again, this time more precisely. “This sea, now a long arm of the Western Ocean, remained.”

He walked over to the next map, drawing the tourists with him. “Things stayed like that until about six and a half million years ago. Then, as that southwest section of the Great Continent kept drifting northward, a new range gradually pushed up here, at the western outlet of that inland sea. When it was cut off from the Western Ocean, it began to dry up: it lost more water by evaporation than flowed into it from its rivers. Now if you’ll come along…” The third map had several overlays, in different shades of blue. “The sea took about a thousand years to turn into the Bottomlands. It refilled from the Western Ocean several times, too, as tectonic forces lowered the Barrier Mountains. But for about the last five and a half million years, the Bottomlands have had about the form we know today.”

The last map showed the picture familiar to any child studying geography: the Trench of the Bottomlands furrowing across the Great Continent like a surgical scar, requiring colors needed nowhere else on the globe to show relief.

Radnal led the tourists out to the donkey corral. The shaggy animals were already bridled and saddled. Radnal explained how to mount, demonstrated, and waited for the tourists to mess it up. Sure enough, both Highhead girls put the wrong foot in the stirrup.

“No, like this,” he said, demonstrating again. “Use your left foot, then swing over.”

The girl who had smiled at him succeeded on the second try. The other balked. “Help me,” she said. Breathing out through his beaky nose in lieu of sighing, Radnal put his hands on her waist and all but lifted her into the saddle as she mounted. She giggled. “You’re so strong. He’s so strong, Evillia.” The other Highhead girl — presumably Evillia — giggled too.

Radnal breathed out again, harder. Tarteshans and other folk of Strongbrow race who lived north of the Bottomlands and down in them were stronger than most Highheads, but generally weren’t as agile. So what, either way?

He went back to work: “Now that we’ve learned to mount our donkeys, we’re going to learn to dismount.” The tourists groaned, but Radnal was inexorable. “You still have to carry your supplies from the omnibus and stow them in the saddlebags. I’m your guide, not your servant.” The Tarteshan words carried overtones of I’m your equal, not your slave.

Most of the tourists dismounted, but Evillia stayed up on her donkey. Radnal strode over to her; even his patience was fraying. “This way.” He guided her through the necessary motions.

“Thank you, freeman vez Krobir,” she said in surprisingly fluent Tarteshan. She turned to her friend. “You’re right, Lofosa; he is strong.”

Radnal felt his ears grow hot under their coat of down. A brown-skinned Highhead from south of the Bottomlands rocked his hips back and forth and said, “I’m jealous of you.” Several tourists laughed.

“Let’s get on with it,” Radnal said. “The sooner we get the donkeys loaded, the sooner we can begin and the more we’ll see.” That line never failed; you didn’t become a tourist unless you wanted to see as much as you could. As if on cue, the driver brought the omnibus around to the corral. The baggage doors opened with a hiss of compressed air. The driver started chucking luggage out of the bins.

“You shouldn’t have any problems,” Radnal said. Everyone’s gear had been weighed and measured beforehand, to make sure the donkeys wouldn’t have to bear anything too bulky or heavy. Most people easily shifted their belongings to the saddlebags. The two Highhead girls, though, had a night demon of a time making everything fit. He thought about helping them, but decided not to. If they had to pay a penalty for making the supply donkeys carry some of their stuff, it was their own fault.