Exploring Blue Ridge Flora and Geology

On November 13, the Rivanna Chapter of Virginia Master Naturalists and friends from the Native Plant Society went on a stroll to learn more about the flora and geology of the Blue Ridge Mountains.

The crew of nearly forty people explored the Jack Albright Trail (opened 2005) and the old Appalachian Trail near Humpback Rocks. Chip Morgan was the guide, and he was assisted by Russell Fitzgerald who shared the history of the local people from the long association his family has with this area.

During the hike the large group stopped frequently. The Catoctin formation meta-basalts are well known for the floral diversity they can support. The landscape in this area is also traced with a variety of features that echo human activity. This was a complex landscape, one that was impossible to soak up in a single day!

Below you will find a list of trees, ferns, a geologic description (map showing paleogeography included), and a link to a prior blog story exploring the geology and flora of Humpback rocks.

List of trees and shrubs observed:

1. Northern Red Oak, Quercus rubra

2. Chestnut Oak, Quercus prinus

3. Black Oak, Quercus velutina

4. White Oak, Quercus alba

5. Pignut Hickory, Carya glabra

6. Mockernut Hickory, Carya alba

7. Yellow-Poplar, Liriodendron tulipifera

8. White Ash, Fraxinus americanus

9. Black Birch, Betula lenta

10. American Linden, Tilia americana

11. Black Locust, Robinia pseudoacacia

12. Red Maple, Acer rubrum

13. Striped Maple, Acer pensylvanicum

14. Norway Maple, Acer platanoides

15. Black Cherry, Prunus serotina

16. Persimmon, Diospyros virginiana

17. Paulownia, Paulownia tomentosa

18. Spicebush, Lindera benzoin

19. Pinxterflower, Rhododendron periclymenoides

20. Alternate-leaf dogwood, Cornus alternifolia

21. Mapleleaf viburnum, Viburnum acerifolium

22. Hop Hornbeam, Ostrya virginiana

23. Sassafras, Sassafras albidum

24. Witch-hazel, Hamamelis virginiana

25. Serviceberry, Amelanchier sp.

26. American Dogwood, Cornus florida

27. Hawthorn, Crataegus sp.

28. Black Haw, Viburnum prunifolium

29. American Chestnut, Castanea dentata

List of Ferns Observed

1. Rockcap fern, Polypodium virginianum complex
2. Christmas fern, Polystichum acrostichoides
3. Marginal wood fern, Dryopteris marginalis
4. Ebony spleenwort,Asplenium platyneuron
5. Upland brittle bladderfern, Cystopteris tenuis (leaves not present, but habitat pointed out)

Geologic description (adapted from USGS description; source below*):

Rock Type: Metabasalt (Catoctin Formation)

Age: Proterozoic Z-Cambrian

Paleo-geographical map (Notice the character and location of the terrain during the time of these basalt flows!!) http://jan.ucc.nau.edu/~rcb7/namPC550.jpg

Description: grayish-green to dark-yellowish-green, fine-grained, schistose chlorite- and actinolite-bearing metabasalt, commonly associated with epidosite segregations.

Minerals: chlorite + actinolite + albite + epidote + titanite +/- quartz + magnetite. Relict clinopyroxene is common; biotite porphyroblasts occur locally in southeastern outcrop belts.

Geophysical signature: The Catoctin as a whole has a strong positive magnetic signature. However, between Warrenton and Culpeper the lowest part of the Catoctin, which consists of low-titanium metabasalt and low-titanium metabasalt breccia, is non-magnetic, and displays a strong negative anomaly. Metabasalt is by far the most widespread unit comprising 3000 feet or more of section

Primary volcanic features : vesicles and amygdules, sedimentary dikes, flow-top breccia, and columnar joints, relict pillow structures.

*Source: http://tin.er.usgs.gov/geology/state/sgmc-unit.php?unit=VACAZc;0

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Prior posting that may be of interest:

Lava Reaching Skyward

The May 1 Byrom Park Bioblitz, species noted by Team 10

The Central Virginia Blue Ridge has a new forest preserve on the way. On May 1, a large group of scientists and naturalists (60+) descended upon the area for a preliminary biological assessment. I was on team 10, and here are some of the things we saw.

-On the eastern flank of the Blue Ridge in Central Virginia
-Lat/long: 38.227902,-78.660403

-Elevation survey range (Trail E) 1270' -1850'

-Survey Team #10

Geology
-Catoctin Formation (Metabasalt)
-Charnockite
At site E-10, in the stream, there were large and beautiful specimens of microcrystaline quartz ranging from bright greens to deep reds. This very well could have been a material source for Native Americans.


Noteable Habitats
Wildflower meadow (E-1). This spot is unusual in that it is a bit of a flat area on the mountainside. The bedrock is the mafic and mineral rich Catoctin greenstone, probably adding to the diversity at the site. This habitat would be a good wildflower destination, particularly for its thick grove of showy orchis, but also for the dozen or so other wildflowers that are blooming there on May 1.



Mafic Boulder (E-2).

Wildflowers
The woods were full. Most of these were observed at site E-1, at the top of the E trail.


Indian Cucumber Root (not in bloom)
Jack-in-the-Pulpit
Showy Orchis
False Solomon's Seal (budding)
Early Meadow Rue
Tall Meadow Rue
Perfoliate Bellwort
Wild Geranium
Pink Lady's Slipper (along E trail at elevation 1320 +/-)
Early Saxifrage
Puttyroot Orchid (***past bloom***). A reader more knowledgable than I pointed out that this plant flowers after the leaves die back! So, this plant was NOT past bloom.


Ferns
Common Polypody (growing on the giant mafic boulder, E-2)
Cut-leafed grape fern

Amphibians

American Toad
Northern Dusky Salamander
Seal Salamander
Southern Two-lined Salamander
Eastern Red-backed Salamander
White spotted Slimy Salamander
Eastern Newt, red eft stage


Mammal tracks
Bear scat
Bobcat urine...territory marker (pee -yhooo!). (At E-8)

Trees
Giant White pine (E-8) circ. 8', 5".
Giant Chestnut Oak (E-9) circ. 10', 6".
Groves of slippery elm, witch hazel, spicebush
A low elevation striped maple

Other
Canadian Owlet moth caterpillar (on the early meadow rue)
Gold Brown Rove Beetle (in the bear scat)

Lava reaching skyward

This past Sunday, a group of us Charlottesville folk went to Humpback rocks up on the Blue Ridge (mile 5.8 on the Blue Ridge Parkway). We enjoy being within a twenty minute drive of these higher elevations...and we aren't alone. The parking lot was packed, and the nearby by living farm exhibit gets year around attention. The trip up there is always amazing because the landscape changes so dramatically before ones eyes...and your ears "pop". Interstate 64 climbs diagonally up the mountain cutting through thick deposits of metamorphosed lava. We were time travelers ...traveling forward in time to see denuded trees that will dominate our view down on the Piedmont in a couple of weeks; our trees are still hanging on to leaves...especially the oaks, hickories, and invasives (pawlonia, white mulberry, etc.). We were also traveling through a complex geologic landscape, ultimately ending up in meta-basalts deposited when central Virginia was well south of the equator, and turned 90 degrees east! (Check this map out)

We all met at the parking lot, the kids poured out, and off we went into a woods known for its high black bear population. Some estimates claim that 3 bear live upon every 2 square miles of woods....that's quite a bit. The nearby Shenandoah National Park boasts the largest population of black bears in the east. This is not the time of year to see them though...late spring and early summer is when you can catch them moving about as mating season kicks in.
An immediate thing noticed when one looks up from the parking lot is that a strenuous hike is about to be had. The hike covers over 1000 feet of elevation in less than a mile...with some mild rock climbing thrown in there. Half our kids had to be carried. The others had something else in mind....a race to the top!
We moved up the mountain, over outcroppings of 570 million year old Greenstone (young for Blue Ridge Rocks!). These rocks are old lava flows that once covered great amounts of what are today Virginia and Maryland. The rock is hard, very hard, and thus resists erosion. This greenstone holds up most of the peaks and ridges for most of the way thirteen miles south and over a hundred miles to the north.
The forest was dominated by Northern Red Oak, Chestnut Oak, and Hickory(mockernut, pignut, and shagbark). Sweet Birch, Witch Hazel, and Hophornbeam were the dominant understory trees. A few old field relics were scattered about in the forest, including large Flowering Dogwoods and Black Locusts, which were probably the oldest trees we saw at Humpback.

One of the familiar and signifying attributes of the dying black locusts is the polypore it plays host to, the Cracked Cap Polypore. So far as I know, it only grows on the Black Locust!

Along the trail we occasionally encountered enormous Chestnut Oaks. Check out the size of the one John's leaning on! Also notice the very distinct bark of the Chestnut oak...so deeply furrowed.

We also found several witchhazel in late bloom (see image with the inset), all but a few had dropped their long and wispy yellow petals and stamens, leaving behind these curved sepals.

All adults and kids (all five under the age of 5) made it to the top! I've tried this on two other occasions, without luck. Must have been somethin in the air! The view was magnificent.