Depends partly on how much of an effort scientifically oriented sophonts feel is worth making, passed banally through her mind. The galaxy’s so huge, so various, and always so mysterious.

Odd, how high and steep the riverbanks were. In fact, it flowed at the bottom of a rocky canyon. Farther inland, its sides were low, begrown to the very edge of the water. Only as she neared did she see that here the stream had broadened to almost a kilometer.

She reviewed the local geography as scanned by a satellite. Flowing westward, the river became wider still. Fifty kilometers hence its estuary was salt marshland. There it emptied into a channel that in turn led to an ocean.

Evidently local topography had made it cut this gorge. Hadn’t that taken time on a geological scale? But the rock wasn’t wind-sculpted, merely littered with boulders where ledges and cracks offered resting places.

Nor was the ground above richly forested, like upstream. A strip of thin, poor, rocky soil reached back some fifty meters from either verge. Tough-looking, deep-rooted little bushes stood sparsely, interspersed with lesser plants that she guessed were evanescent opportunists. She saw just a few tiny animals scuttering between, though winged creatures continued plentiful. The camp was at the edge of the semi-desert, half surrounded by fairly large shrubs, trees behind it.

One of countless puzzles.… At the moment, she had too much else to think about. Surely in due course somebody would reason this out.

She eased her pace. In spite of a noticeably denser atmosphere and higher partial pressure of oxygen, in spite of her being in athletic condition and having trained beforehand, a surface gravity fifteen percent above Earth normal added nine kilos to her weight.