Wolf Rock, Chimney Rock

Turkey Vultures were kettling above the toll road to Leesburg as I set out for Catoctin Mountain Park in Frederick County, Maryland on this unnaturally warm and sunny November day. Some hiking, some field work in support of the paper that I am writing about the park for my geology class.

From the visitors’ center, I followed the clockwise loop suggested by PATC trail guides. The trails in the park are not blazed, but are wide and generally easy to follow, even when covered with the hazard of the season, slippery leaf litter. The side trip to Cunningham Falls is perhaps not worth the bother: the way to the falls is popular and boardwalked.

pines prevailview to the westBack on the main circuit, I climbed to the Blue Ridge Summit Overlook (600′ from my starting point), snapping images of the Catoctin metabasalt. Crossing back to the east, I entered the region of the Weverton quartzite, exposed as Wolf Rock (at left) and Chimney Rock. I found a nice small boulder of Weverton conglomerate, too. Mountaintop bird life was sparse: I was a little surprised to find no juncos. A raven quorked along the way; a nuthatch didn’t seem concerned; a Pileated Woodpecker was rattling the doorknobs of a pine tree.

A little pressed for time and daylight, I followed the guide’s backtrack route, getting back to the car in 3:50, covering about 7.5 miles. My notes say that I covered a 8.3-mile circuit in 1995 in 3:30. I guess those were someone else’s legs.

Blue Ridge, Ridge and Valley

The sun was burning off the morning fog, residue from our several days of rain, as we set off northwest on I-270 on this car-powered field trip, stopping at nearly a dozen places in the Blue Ridge and Ridge and Valley provinces. We were again led by the local naturalist community’s answer to John Malkovich, the equally intense, hyper-organized Joe Marx.

at the Pier OneOur first stop was actually still in the Piedmont, in the parking lot of a Pier One Imports in Frederick, just down the U.S. 40 strip from the Barbara Frietchie restaurant. We looked at the Leesburg Member of the Balls Bluff Siltstone, a breccia composed of broken material from an alluvial fan under conditions similar (except for aridity) to those in the eastern edge of Death Valley. The boulders in the image were broken off from the bedrock and placed by construction activity.

greenstonefrom the Tea RoomIn class lectures, we’ve just been introduced to the various metamorphic rocks, so the timing of this field trip was apt. Moving farther west into Frederick County and into the Blue Ridge province, we explored the formations that make up the South Mountain Anticlinorium: a metagranite; the Catoctin Formation (composed of epidote-rich greenstone, a metabasalt); and the Weverton Formation, a sandstone metamorphosed to quartzite. We checked out the Weverton at Gambrill State Park from the grounds of an amenity known as the Tea Room. Nice views. Bluebirds, juncos, and lady beetles greeted us at the park. Moving on to Boonsboro, we stopped for the Loudoun Formation (phyllite) and the Harpers Formation (shales and phyllite).

Wilson BridgedolomiteContinuing west, we entered the Ridge and Valley province. Our first stop was at the stone Wilson Bridge, built in 1819 by Silas Harry (and rehabbed in 1984 by LeRoy E. Myers) to carry the National Road across Conococheague Creek. Bedrock here is limestone and shale, and the creek follows the shale (lest it dissolve its bed of limestone). On the west side, up a short hill, are outcrops of the Pinesburg Station Dolomite (ca. 472 Ma) and the Chambersburg Limestone (just younger, 472-461 Ma). The dolomite, uptilted into almost vertical layers, laced with shale, is pictured.

weatheredposter childPushing on the last of the season’s acid-yellow maples, we came to the Martinsburg Formation, a fissile (breaks in your hands) shale interbedded with graywacke. This turbidity-current deposit was first named by Swiss shepherds as flysch. And then continuing past Hancock, we came to the Western Maryland railroad cuts. The railroad ran parallel to the C&O Canal. When the cuts were made in the rock, ca. the beginning of the 20th century, the intricacies of folding captivated geologists and the lay public. Now the rocks are heavily weathered, but you can still see the lines of synclines and anticlines. At right, the line of white aligned with Joe’s head is an intrusion (perhaps from groundwater) of calcite.

big synclinelooking westWith the light fading, we wrapped up at the new poster child for geology, the giant road cut for I-68 through Sideling Hill. Even with the poor photographic conditions, the lines of the syncline (U-shaped) that form the top of the ridge are unmistakeable. Joe pointed out that it’s very rare for a ridgetop to be formed from an anticline (A-shaped), despite one’s intuition. Rocks stretched over the apex of an anticline break and quickly erode. Rather, what we observe is either a syncline (the rocks are compressed at the bottom of a fold and are somewhat more resistant to erosion) or a breached anticline (the apex is broken off), making two mirror-image ridges. Indeed, the whole of the South Mountain Anticlinorium is one such breached anticline, forming the Blue Ridge/South Mountain to the northwest and Catoctin Mountain to the southeast. The aha! of the trip was Anne’s, as she worked out just how immense the folded layers of rock would have to be to put the summit of Sideling Hill at the bottom of those folds. Our rocks here are the Rockwell Formation, and below that, the Purslane Formation.

Piedmont and Coastal Plain

After a gloomy, drizzly start, the wet weather held off and we had a great field trip, led by Joe Marx, exploring several sites of geological interest in the Four Mile Run and Holmes Run stream valleys in Arlington County and Alexandria City.

the view from the castleSetting out from East Falls Church Metro in the Piedmont, we paused to look at a cut in the stream bed of Four Mile Run to check out the alluvial layer from the last glaciation. The run slithers under I-66, skirting the so-called Brandymore Castle. At Joe’s fast pace, we climbed the castle, actually a lens of quartz from the middle Ordovician that protrudes into the landscape. The bedrock here is the Sykesville formation, a Cambrian schist, with bits of an even older actinolite intruding into it, and we found examples of both.

After a quick trip to Rosslyn to climb the first of five Tertiary period upland gravel terraces (the fifth and oldest forming the hill at Tysons Corner), we returned to Four Mile Run, farther downstream at the Long Branch Nature Center. We took a lunch break and indulged in some geology humor (Q: Where can you find the floodplain in Arlington County? A: Look for the picnic tables.) and did some sorting in the parking lot so that participants in Cliff Fairweather’s galls workshop got where they wanted to be. We stopped at Carlin Springs, now dry, but once a 19th-century resort stop on the W&OD railroad.

potholesalong the reachThe high point of this stop was visiting a lovely cascade of Four Mile Run, relatively unmanaged and unchannelled, known as Hoffman’s Reach (sp?). Here the stream has carved potholes in the Cambrian-period Indian Run formation; granite intrusions into the pale gray rock are visible in the photos. Joe also pointed out a good example of the bedrock decaying into saprolite; a soil scientist, working top-down from the other direction, would call this the C horizon, which is quite thick in this area.

the boundaryOur capstone stop was at the tiny sliver of a park in Alexandria named for Dora Kelley. Here, in the steep cut of a gully formed by a tributary of Holmes Run, Joe turned up an instance of the gravelly Potomac formation of the Coastal Plain (from 125 Mya) lying on top of the metasandstone of the Indian Run formation (from about 500 Mya). In the image, Joe is standing on loose gravel in the gully, and the rock exposure is behind him. The top horizontal edge of the dark, solid Indian Run rock is about even with Joe’s mid-thigh, and the layers of Potomac formation (gravel to clay) lie above.

Hawksbill Mountain circuit

driving upThrough Virginia horse and wine country (every time I come through there’s a new winery offering tastings) to the big Park straddling the Blue Ridge, with a pause for this wonderful combination of wayfinder signs using “Freeway Gothic” and Clearview together.

from Hawksbill summitI devised a bowtie circuit starting from the Hawksbill Gap parking area: up the steadily steep trail to the Hawksbill Mountain summit, down the Salamander Trail to the Appalachian Trail, the AT north to the stables at Skyand, returning via the bridle path, Limberlost Trail, and Crescent Rocks Trail, with a quick side trip to my special place on the Ridge, Betty’s Rock. I’m estimating the mileage at 8.0; I went around in 4:20, and made the 680-foot climb of the mountain in about 25 minutes. Yay me.

on the trail againExcept for the climb, the trails are fairly level, and the AT is not too rocky, at least mostly. Fall colors are still developing: I saw yellows and golds stirred into the pale green, with the occasional maple or sumac or poison ivy to provide a shot of red. Ravens and juncos constituted most of the bird life. One mixed flock of songbirds with a mystery warbler—perhaps a parula. A nuthatch calling very fast, in a ank-ank/ank-ank/ank-ank rhythm. Ground squirrels were very conspicuous, though they tried not to be.

out of the rocksmountain-ash, closerOn the northwest side of the ridge, thriving in the poor soils of the talus fields, I found several stands of Mountain-ash, probably American (Sorbus americana), though the fruits are definitely red, not orange (per Petrides).

News from the park

Some tidbits from the most recent newsletter from Friends of Huntley Meadows Park:

  • The crayfish population is up! Resource Management Intern Alice Millikin writes that water quality monitors as well as turtle and frog trappers reported increases. The nets used for water quality monitoring caught 28 individuals, more than the catch for the past five years combined.
  • King Rails (Rallus elegans) are back! Park Manager Kevin Munroe says in his message that a parent with four or five chicks was seen at least three times in the period 19 July to 27 July. Higher water levels, a habitat mosaic created by muskrats and beavers, and increased crayfish numbers are responsible.
  • Construction for the wetland restoration project has been delayed again. A dam breach analysis was recently completed, with the anticipation that the project can be qualified as low-hazard, and hence move through the permitting process. A 2010 date for construction is still possible, but 2011 is more likely.
  • Also in 2010-11, the surface and toe boards of the boardwalk will be replaced, this time with recycled plastic materials. Lower maintenance, and a greener message. The project is funded by the 2008 bond referendum.

Seneca Creek Greenway Trail, northern section

lunch breakToday’s hike was a leisurely 8 miles (though we had expected 6) up the Seneca Creek Greenway Trail, organized by ANS and led by Bob Pickett. We began where Seneca Creek crosses Brink Road and worked our way upstream, then climbed out of that watershed to follow the Magruder Branch up to its crossing of Valley Park Drive, just south of Damascus in upper Montgomery County, Maryland.

slipperyThe hiking is easy, with just a little elevation change. There is one slippery crossing of Magruder Branch which we all managed to varying degrees of dryness. The upper reaches of the trail we followed, above Log House Road, lie within Damascus Recreational Park, and consist of accessible asphalt and boardwalk.

big treeBob’s strength is the green stuff, so we botanized great and small, including this huge White Oak (Quercus alba). We found some individuals of another as-yet-unidentified oak species, something resembling Shingle Oak (Q. imbricaria); one of its saplings is visible in the image, between Bob and the big tree. Among the wildflowers blooming in late June, Bob pointed out a yarrow, Water Hemlock, Fringed Loosestrife, Deptford Pink (I gotta learn how to do macro with my point and shoot). The wet bottomlands yield half a dozen species of ferns. I learned that the green case of an immature Mockernut Hickory (Carya tomentosa), when scratched, smells wonderful.

invasiveOur destination species, if you will , was found in several patches north of Log House Road. Wavyleaf Basketgrass (Oplismenus hirtellus ssp. undulatifolius) is a new invasive of particular concern in Maryland. Perennial, shade indifferent, and propagated by seeds that can attach themselves to passing mammals, the plant has a lot of weapons at its disposal. The patch in this image was recently treated with a herbicide, but we found another untreated patch nearby.

A colloquy of nuthatches met to discuss our lunch break. Acadian Flycatchers and Wood Thrushes were numerous, if not easy to spot.

At the park: 31

box #2box #68Last weekend, I did a spot check of the last two nest boxes, and was gratified that both were successful. Box #2 (at left) hatched out eight Hooded Merganser eggs, and box #68 (at right) hatched eight Wood Duck eggs, with one unhatched. For the season, our totals are down a little bit from last year, which had seen a big spike in Wood Duck activity. In 2009, we had four Hooded Merganser nests, three of which hatched out: 39 eggs laid, 29 hatched. We had five Wood Duck nests, all of which hatched out: 61 eggs laid, 59 hatched. Park staffer Dave Lawlor reports one successful nest in the boxes he is monitoring, with nine baby mergs.

the view from box #68spatterdock and egretThe park is a green blast of primary production. Bird activity is subsiding, with only one lazy egret to accent the landscape. I saw a family of Mallards; a Red-shouldered Hawk was screaming an important message to someone. Chris IDs the large-leaved plants in the right image as Spatterdock (Nuphar lutea).

devil gutsSet off by the green is the bright orange of a drift of Dodder (Cuscuta spp.), a parasitic vine that I find absolutely fascinating.

Soldiers Delight

For the holiday, I took a run up I-95 to Soldiers Delight Natural Environment Area, northwest of Baltimore, for a nature stroll.

Stepping on to the trail at the visitors center, in a trice I lost the trail and wandered on to an interpretive trail still under development. The downed trees across the trail and the ticks that tried to hitch a ride on my legs should have been a clue. I had to double back and walk back on the verge of Deer Park Road, and I was caught in a passing rain shower, for my sins.

Choate Mine TrailI had better luck following the trails on the east side of Deer Park Road. Nevertheless, had I brought my hiking boots instead of my birding shoes, I would have been glad of the added support. Birdlife included lots of Field Sparrows and Eastern Towhees and a plus-sized Blue-gray Gnatcatcher; best sighting for the trip was a small group of Cedar Waxings (Bombycilla cedrorum). Heard a possible chat and Pine Warbler.

pink familySoldiers Delight is underlaid by serpentine rock, which yields thin soils short on nutrients and long on toxic metals like chromium, so the plant communities are distinctive, as well as the animals that depend on them. Most of the wildflowers will have to wait until my ID skills improve, but here I’m pretty sure that we are looking at Serpentine Chickweed, a subspecies of Cerastium arvense, found in one of the grassland areas.

downstreamIn the woods, I found a Little Wood-Satyr (Megisto cymela), described as abundant in my field guides but nevertheless new for me.

At the park: 30

I had intended to show Dirk the nest box with Tufted Titmouse eggs in it, but we were surprised to find that the eggs had already hatched and the nest comprised six gaping, blind mouths.

As for the intended residents, Box #13 hatched out 13 Wood Duck eggs. A merganser family of hen and three ducklings, practicing diving, was spotted this morning; possibly this is the same family of thirteen that hatched on 17 April.

Four boxes in a row along lower Barnyard Run are due to hatch out soon, probably this week. We then have two remaining boxes to hatch in June: #2 at the head of the main pond (Hooded Merganser) and #68 at the far end (Wood Duck).

New bird arrivals detected over the past couple weeks: Chimney Swift, all three swallows, Wood Thrush, Yellow-billed Cuckoo, Acadian Flycatcher, and a Brown-headed Cowbird chasing insects in the parking lot as bold as any urban Rock Dove.

At the park: 29

The subject of my term paper for the Introduction to Ecology class that I recently completed is Huntley Meadows Park. The paper is a little long on data and short on analysis, but I’m happy with it. From the introduction:

Huntley Meadows Park comprises approximately 1,425 acres (577ha) of freshwater wetland and surrounding forest in southern Fairfax County, Virginia. Managed by the Fairfax County Park Authority (FCPA), it is the County’s largest park, and features the largest (70+ acres, 28+ ha) non-tidal marsh in the area. Bounded by housing subdivisions to the north, east, and south, and government installations to the west and southwest, the Park is an island of blue and green prized by casual strollers and scientific specialists alike. It is particularly valued by naturalists for the unique diversityof the habitat to be found there, especially considering its urban/suburban surroundings. Guidebook writers and editors like Scott Weidensaul [Weidensaul92] and David W. Johnston [Johnston97] have singled out the Park for special attention, noting that its mix of woods and water makes it a popular spot for Big Day birders; Weidensaul calls the Park’s very existence “utterly improbable,” encroached on as it is by the busy traffic corridors of U.S. 1 and Interstates 95 and 495. The main entrance to Huntley Meadows Park is only three miles from the Huntington terminus of Metro’s Yellow Line, and hence the Park is a short trip from anywhere in the Washington, D.C. metropolitan area.

At the park: 28

lone egretadaptive reuseMaples are leafing out, offering some shade in the unseasonal midsummer heat. Frogs are everywhere, including a pair of Green Treefrogs (Hyla cinerea) resting inside our one plastic nest box. At least something is getting some value from it. New arrivals seen/heard/reported: Yellowlegs sp., Solitary Sandpiper, Great Crested Flycatcher, White-eyed Vireo, Red-eyed Vireo, Yellow Warbler, Prothonotary Warbler (a singing male and a no-bins look at a foraging female), Ovenbird. A Tufted Titmouse is squatting in box #5 again.

At the park: 26

New cattail growth is ankle-high, and the understory in the forest is starting to green up. We had our first box hatch out on Friday (according to reports from a photographer), and the hen and thirteen ducklings put on a show skittering about the main pond this morning. Unfortunately, we’ve also had our first nest failure, as box #3 has been predated and the remaining two eggs abandoned. Common Yellowthroats and American Coots made their first appearance this week; Blue-Gray Gnatcatchers were numerous. Myra found a Meadow Vole (Microtus pennsylvanicus) feeding by the boardwalk.

In past weeks, at least one Virginia Rail (Rallus limicola) has been audible and fleetingly visible, and a passing-through Sora (Pozana carolina) was reported the week of March 29. Jennifer spotted a Beaver on that trip, too. Common Snipe and Great Egrets have also arrived.

At the park: 24

When I was a kid, attending Saturday morning training to be confirmed in the faith as a Lutheran, we would take a break at mid-morning. The second year of this training was led by the pastor of this brassbound Missouri Synod congregation (someone else took the first year), and it was held on the site of the new church that was being built, farther out in the suburbs. (The new church building, which dwarfed the old building on Peach Orchard Avenue in Oakwood, was Orwellistically known as “the chapel.”) So pastor’s idea of taking a break was for us kids to scour the fields around the building site looking for small stones that would get in the way of groundskeeping. This was known, without euphemism, as “picking rock.”

I never finished confirmation, but how much this exercise had to do with my decision is hard to say.

Anyway, now I am an adult, and what do I do with my Sunday mornings, “for fun”? Pick trash out of the stream floodplain, and maybe look at some birds along the way.

20 minutes of workWe had a full team this morning, so I sent Myra and Jennifer on up to boxes #6 and #84 while I scrubbed the western bank of Barnyard Run as it opens up into the wetland. I pulled a small shopping bag of stuff out, mostly bottles and cans and broken bits of styrofoam, but also a very weary basketball. A lot of this is litter by thoughtless people, but much of it also is just escaped rubbish—an animal tears open a trash bag, for instance—from the housing subdivisions along South Kings Highway that finds its way downstream.

Not much new happening in the boxes yet: just #7, which is now incubating. Myra found a couple of Brown Thrashers and the first Tree Swallows of the season.