To quote Alfred Tennyson, "Nature, red in claw and tooth" is the Great Adversary in Barr's mystery novels. Certainly, the psycho murderers and eco-criminals prowling the primeval forest give Nevada Barr's character, Anna Pigeon, a park ranger, lots of trouble; though, human villains are but sickly irritants in comparison with the rage of Mother Nature. Volcanic eruptions, forest fires, and, in this Borderline, flash floods menace to dry the earth's crust clean, with no a care for other people -- Anna is among them -- facing the catastrophe. By now, a typical woman would have resigned the National Park Service and satisfied the call of the nature by reading National Geographic. But, Anna is no typical woman: Anna Pigeon is a menopausal Amazon woman in khaki carrying the wild within her and manages to kick some butt as hers is sagging. 
In "Borderline," Pigeon is on leave, recovering from an especially ghastly near-death experience in Royale National Park, which was the "Winter Study" subject preceding mystery in the series. Being Anna, she decides to cure by rafting the Rio Grande down. Accompanying her are Paul Davidson, her new husband, and a bunch of college children ranging from whiny to cheerful. No sooner do they set out than whitewater and a rickety coed result in raft capsizing, booting out the rogue cow that Anna has rescued. Then Anna spots an almost-dead pregnant woman. With her dying blessing, Anna performs a knife C-section to deliver an infant girl. Is it enough for help dissertation or dissertations writing?