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 HumpbackRocks. 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, Paulowniatomentosa
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
Rockcap fern, Polypodium virginianum complex
Christmas fern, Polystichum acrostichoides
Marginal wood fern, Dryopteris marginalis
Ebony spleenwort,Asplenium platyneuron
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. Metabasaltis 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
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!
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
,
, and Hickory(
,
, and
).
,
, and
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
. 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.
