TWO

       Abrupt Climate Change

       The ground is mud. There are a few sandstone rocks scattered here and there, and some river-rounded chunks of amber quartzite, but for the most part, mud. Hard enough to walk on, but dismal to sit or lie on.

       The canopy stands about a hundred feet overhead. In the summer it is a solid green ceiling, with only isolated shafts and patches of sunlight slanting all the way to the ground. The biggest trees have trunks that are three or four feet in diameter, and they shoot up without thinning, putting out their first major branches some forty or fifty feet overhead. There are no evergreens, or rather, no conifers. No needles on the ground, no pinecones. The annual drift of leaves disintegrates entirely, and that’s the mud: centuries of leaf mulch.

       The trees are either very big or very small, the small ones spindly and light-starved, doomed-looking. There are hardly any medium-sized trees; it is hard to understand the succession story. Only after Frank joined FOG did he learn from one of his associates that the succession was in fact messed up, its balance thrown off by the ballooning population of white-tailed deer, whose natural predators had all been eradicated. No more wolf or puma; and so for generations now the new young trees had been mostly eaten by deer.

       Big or small, all the trees were second or third growth; the whole watershed had been clear-cut before the Civil War, and during the war the guns of Fort DeRussey, at the high point of the park near Military Road and Oregon Avenue, had a clear shot in all directions, and had once fired across the gorge at a Confederate scouting party.

       The park was established in 1890, and developed with the help of the great designer Frederick Law Olmstead; his sons’ firm wrote a plan at the end of the First World War that guided the park through the rest of the twentieth century. Now, in the wake of the flood, it appeared to have reverted to the great hardwood forest that had blanketed the eastern half of the continent for millions of years.

       The muddy forest floor was corrugated, with any number of small channels appearing in the slope down to Rock Creek. Some of these channels cut as deep as thirty feet, but they always remained mud troughs, with no stony creekbeds down their middles. Water didn’t stay in them after a rain.

       The forest appeared to be empty. It was easy to hike around in, but there was little to see. The animals, both native and feral, seemed to make efforts to stay concealed.

       There was trash all over. Plastic bottles were the most common item, then glass bottles, then miscellaneous: boxes, shoes, plastic bag scraps … one plastic grocery bag hung in a branch over Rock Creek like a prayer flag. Another high-water mark.

       There were many more signs of the flood. Most of the park’s roads, paths, and picnic areas had been located down by the creek, and so were now buried in mud or torn away. The gorge walls were scarred by landslides. Many trees had been uprooted, and some of these had been caught by the Boulder Bridge, forming a dam there that held a narrow lake upstream. The raw sandstone walls undercut by this lake were studded with boulders emerging from a softer matrix. All over the forest above these new cliffs, windrows of downed trees, root balls, branches and trash dotted the forest floor.

       The higher roads and trails had survived. The Western Ridge Trail extended the length of the park on its eponymous ridge, and was intact. The nine numbered cross-trails running down from the ridge trail into the gorge now all ended abruptly at some point. Up north near the Maryland border, the Pinehurst Branch Trail was gone, its creekbed ripped like the main gorge.

       Before the flood there had been thirty little picnic areas in the park, ten of them reserved for use by permit. The higher ones were damaged, the dozen on the creek gone. Almost all of them had been paltry things, as far as Frank could determine in the aftermath – small clearings with picnic tables, fireplaces, a trashcan. Site 21 was the worst in the park, two old tables in perpetual gloom, stuck at the bottom of a damp hollow that ran right onto Ross Drive. With that road closed to traffic, of course, it had gained some new privacy. Indeed in the mud under one table Frank found a used condom and an item of women’s pink underwear, Disney brand, picture of Ariel on waistband, tag saying Sunday. Hopefully they had had a blanket with them. Hopefully they had had fun. The condom seemed a good sign.

       East of site 21 the drop to the creek was steep. The big trees that had survived overhung the water. Sandstone boulders as big as cars stood in the stream. There was no sign of the gravel path the map indicated had run up the western bank, and only short stretches of Beach Drive, a two-lane car road which had paralleled it on the eastern side. Above a flat-walled boulder, set crosswise in the stream, tall trees canted out over the creek into the open air. Across the ravine was a steep wall of green. Here the sound of the creek was louder than the sound of the city. If Beach Drive stayed closed to traffic, as it looked like it would, then water would remain the loudest sound here, followed by insects. Some birds were audible. The squirrels had grey fluffy backs, and stomachs covered with much finer fur, the same gold-copper color as the lion tamarins still missing from the zoo.

       There were lots of deer, white-tailed in name and fact, big-eared, quick through the trees. It was a trick to move quietly through the forest after them, because small branches were everywhere underfoot, ready to snap in the mud. People were easier to track than deer. The windrows were the only good place to hide; the big tree trunks were broad enough to hide behind, but then you had to look around them to see, exposing yourself to view.

       What would the forest look like in the autumn? What would it look like in winter? How many of the feral animals could survive a winter out?

      It turned out that Home Depot sold a pretty good treehouse kit. Its heavy-duty hardware allowed one to collar several floor beams securely to trunk or major branches, and after that it was a simple matter of two-by-fours and plywood, cut to whatever dimensions one wanted. The rest of the kit consisted mostly of fripperies, the gingerbread fill making a Swiss Family allusion that caused Frank to smile, remembering his own childhood dreams: he had always wanted a treehouse. But these days he wanted it simple.

      Getting that was complicated. For a while he left work as early as he could and drove to one edge of the park or another, testing routes and parking places. Then it was off into the park on foot, using a Potomac Appalachian Trail Club map to learn it. He hiked all the trails that had survived, but usually these were just jumping-off points for rambles in the forest and scrambles in the gorge.

      At first he could not find a tree he liked. He had wanted an evergreen, preferably in a stand of other evergreens. But almost every tree in Rock Creek Park was deciduous. Beech, oak, sycamore, ash, poplar, maple – he couldn’t even tell which was which. All of them had tall straight trunks, with first branches very high, and crowns of foliage above that. Their bark had different textures, however, and by that sign – bark corrugated in a vertical diamond pattern – he decided that the best trees were probably chestnut oaks.

      There were many of these upstream from site 21. One of them canted out and overhung the creek. It looked as if its upper branches would have a nice view, but until he climbed it he wouldn’t know.

      While making his reconnaissances he often ran into the frisbee golfers, and when he did he usually joined them. In running the course they always passed site 21, and if the homeless guys were there the second vet, whose name was Andy, would shout his abrasive welcome: ‘Who’s winning? Who’s winning?’ The frisbee players usually stopped to chat for a moment. Spencer, the player with the dreadlocks, would ask what had happened lately, and sometimes get an earful in response. Then they were off again, Spencer in the lead, dreadlocks flying under bandana, Robin and Robert following at speed. Robin sounded like some