Sunday, November 12, 2pm. We will practice tree and moss identification on this family-friendly hike along the one-mile loop trail at Eastwoods Preserve (link to map). Eastwoods was purchased by the Town of Pound Ridge in 2009 and is maintained by a partnership between the Pound Ridge Conservation Board and the PRLC. The forest is rich in Mountain laurel, ferns, moss and often mushrooms, giving it a fairly-land quality. The trails are tighter and more twisting than most, a joy to hike on a fall day. Please register with Krista at firstname.lastname@example.org or call 914-205-3533. Parking is limited at the Preserve parking lot at 134 Eastwoods Road, so please carpool if you can.
In this latest installment of the Pound Ridge Land Conservancy (PRLC) blog, I invite you to explore the vast history of time written in the rocks of Pound Ridge with a focus on the Armstrong Preserve, located in the northwestern corner of town at 1361 Old Post Road. Trails at this preserve are open to hikers every day of the year from dawn to dusk.
To begin, please imagine that your arm represents geologic time, with your shoulder joint being the Big Bang and the tip of your middle finger representing today. Rocks began to form near your elbow and the dawn of life occurred just before your wrist. Between your wrist and the middle of your palm, the prominent bedrock types of Pound Ridge were created by successive waves of mountain-building events. They were then covered and contorted repeatedly, over millions of years, and eventually stripped bare by the glaciers that receded only 20,000 years ago, near the tip of your middle finger on our imaginary time scale. We must look to the wider region and even the other side of the world to piece together this vast history, much of it obliterated by time.
The oldest rock in Pound Ridge is the Fordham gneiss underlying Armstrong Preserve. It was produced 1.1 billion years ago during a Precambrian period called the Grenville Orogeny, when this part of the world was located in the Southern Hemisphere and was turned 90 degree on its side from our current orientation. This collision between then-continents Laurentia and Amazonia caused the rise of a massive mountain range that compressed and deformed existing rock into a Gneiss basement layer that is called the Grenville Province and underlies much of New York.
Gneiss is a high-grade metamorphic rock, formed from either granite or sedimentary layers under intense heat and pressure. It is resistant to weathering and can be seen in the many exposed outcrops of Armstrong as well as in the nearby Ward Pound Ridge Reservation. While variable in color, gneiss displays distinct foliation, or grain, created by alternating layers of its component minerals: quartz, plagioclase, biotite mica, garnet, hornblende and others. The alternating light and dark colors that are so characteristic of gneiss do not represent fossilized sedimentary layers but rather a restructuring and realignment of minerals into layers that are called “gneissic banding.”
The basement layer we now see visible before us was increasingly buried by the sediments of the eroding Grenville Mountains over the next 400 million years, which depressed the land with their great weight and at times were inundated by shallow seas. Then, in the late Ordovician Period, a volcanic island arc approached and slammed into this part of the continent. Called the Taconic Orogeny, it’s pressure created our local Manhattan Schist and Inwood Marble and severely folded the existing bedrock into large ENE-WSW trending ridges and valleys. This or a subsequent episode caused some intrusions of granitic pegmatite in Armstrong’s bedrock as well, which were subsequently folded too.
Life was difficult in New York for the next few million years as continents collided and mountains rose and fell. The Fordham gneiss of Armstrong experienced a third wave of compression and metamorphosis in the Acadian Orogeny followed by another long period of erosion of highlands and sedimentation of lowlands. Folding caused by this event runs in a NNE direction and is difficult to discern from the preceding episode.
The last of the great mountain-building events was the Alleghanian Orogeny, 300 million years ago in the late Carboniferous Period. This fourth collision resulted in the formation of Pangaea and was strongly felt in southeastern New York, where it produced tight folds that reoriented earlier land formations.
The supercontinent Pangaea did not last long before it began to rift apart, resulting in volcanoes and allowing inundation of previously dry land. Evidence from that period is visible in the Hudson River Valley and in the Palisades, but was largely swept clear from Pound Ridge in the Pleistocene: the age of glacial advance and retreat. An ice sheet measuring one-half mile thick ground back and forth across this landscape for nearly 100,000 years, freezing and thawing, cracking rocks and transporting them from mountaintops to the sea. During four long periods of retreat, the glaciers dropped stone inland and created dams and flooding, and a rise in sea levels that brought the sea to our door.
The last glacial ice disappeared from Pound Ridge about 12,000 years ago, leaving behind a roughened and stony landscape that has been little changed by the thin mantle of forest now covering it. We can readily see the glacier’s action in the exposed stony faces of east-facing hills and the till and boulder-strewn west-facing slopes. Glacial erratics are common: there is a huge boulder perched atop a forty foot cliff at Armstrong’s Crow Ledge, tumbled for some distance but now at a high point in the Preserve. There are also several lesser cliffs, some with wonderful gneissic banding and folding, and talus at their bases. The vast majority of rock seen will be Fordham gneiss but there is the possibility of finding any mineral from higher elevations carried here by force of wind or water, or even human.
Keep an eye out for history on the landscape. It has quite a tale to tell, if only we read the clues.
Thank you to Ted Dowey for photographs and assistance with this exploration. I have also relied heavily upon the following published resources:
Robert Titus of Hartwick College, frequent contributor to regional media and author of The Catskills: A Geological Guide. Third edition 2004. (link)
Chet and Maureen Raymo’s invaluable book Written in Stone: A Geological History of the Northeastern United States. Third edition in 2001. (link)
Mehdi Alavi’s 1975 Thesis: Geology of the Bedford Complex and Surrounding Rocks, Southeastern New York. University of Massachusetts, Amherst. (link)
This collection of photographs depicts mushrooms found in Halle Ravine in the last few fall seasons and is a good primer for what we can expect to see on our guided walk on September 24. Registration for that event is filling quickly so please contact Krista by email or by phone (914-205-3533) to register or to cancel and make room for another person to join us.
We have encountered dry weather conditions in most years and therefore find mainly bracket fungi, which are supported by the moisture held in wood. For the difficult to distinguish species, I include several instructive photos from Richard Nadon and others from MushroomExpert.com.
Halle Ravine is a nature preserve protected by the Pound Ridge Land Conservancy and is open for hiking every day from dawn to dusk. Foraging or collection of any form of wildlife is generally prohibited in the Preserve. Trail maps and more information are available at www.prlc.net/preserves.
Volunteers are invited to join our work sessions in both September and October in Carolin’s Grove, where we are working to restore forest to about an acre of storm-damaged woods. On September 9, we will work from 10am to noon to clear areas of invasive Japanese stilt grass to prepare them for planting. On October 14, we will plant grass seed and wildflowers in sunlit gaps to support pollinators and other animals during the transition back to forest. Come back, if you have volunteered here before, and be amazed at what’s growing up in Carolin’s Grove now!
Our summer interns are proud to present to the public on their work and accomplishments this summer with PRLC. Everyone is welcome to attend this inspiring and informative evening in support of our young conservationist interns and volunteers who have done fantastic work all summer to support our mission and protect the environment in Pound Ridge. Light refreshments will be served.
Wednesday, August 16th, 7pm to 8pm. At the Armstrong Preserve and Education Center at 1361 Old Post Road, Pound Ridge NY (link to directions).
Annual Summer Intern Presentations and Thank You to Volunteers
Date: Wednesday August 16, 2017
Time: 7pm-8pm. Refreshments will be served.
Location: Armstrong Preserve and Education Center
1361 Old Post Road, Pound Ridge
For more information and to RSVP, call 914-205-3533 or email email@example.com. All are welcome!
We held two volunteer work sessions for Invasive Species Awareness Week at the Armstrong Preserve and Education Center, where we manage a series of outdoor classrooms as native habitats. Five people attended the Saturday session and twelve came out on Thursday July 13. With 9 students and 3 retired volunteers, plus 3 PRLC board members, we successfully met our goal of removing invasive shrubs from three acres of the Preserve!
Over the course of a few hours on two mornings, we removed barberry, bittersweet, wineberry, mile-a-minute, and more from the Armstrong vernal pool, meadow, and in the forest along the blue and white trails. Additional work by our summer interns will proceed along the yellow trail next. Please sign up at firstname.lastname@example.org to join us.
Concerned organizations in Northern Westchester have scheduled three events in Pound Ridge to
acknowledge Invasive Species Awareness Week, July 9 – 15. On July 11, from 6:45 to 8 p.m., the
Pound Ridge Library, 271 Westchester Ave, and The Invasives Project will host an introduction to
invasive species with a video, Are Alien Plants Bad?, featuring Doug Tallamy. A ‘tasting’ of edible
invasive plants and informal discussion will follow the video. The event is free and open to the
public. Dr. Tallamy, Professor of Entomology at the University of Delaware, is the author of Bringing
Nature Home, the seminal work on the importance of native plants in our ecosystems and the dangers
posed by invasive species.
The second event, sponsored by the Pound Ridge Land Conservancy, is an in-the- field working
session at the Armstrong Preserve, 1361 Old Post Road. On July 13, from 10 a.m. to noon,
volunteers will learn how to identify and manage several invasive plants, including mile-a- minute
weed, phragmites, Oriental bittersweet, Japanese barberry, wineberry, Japanese stiltgrass, garlic
mustard, multiflora rose and others. To register for this event, contact Krista Munger at
The final event, another working session, is sponsored by the Westchester Land Trust and takes
place on July 15 from 9 a.m. to noon at the Zofnass Family Preserve/Westchester Wilderness Walk
in Pound Ridge. Volunteers will be led by the New York-New Jersey Trail Conference’s Strike Force
Linda Rohleder, Lower Hudson Partnership for Regional Invasive Species Management (LH-PRISM)
Phone: 201-512- 9348 Ex. 821
Conservation Corps crew, who will provide on-the- job training, enabling participants to recognize
invasive plants and learn how to manage them on their own properties. Participants should bring
work gloves and drinking water. Please register at http://nynjtc.org/events.
The Invasives Project, Pound Ridge Land Conservancy and Westchester Land Trust are members of
the Lower Hudson PRISM (our local Partnership for Regional Invasive Species Management), a
group of concerned organizations and individuals who work together under the auspices of the New
York State Department of Environmental Conservation to prevent or minimize the harm caused by
invasive species. The eight PRISMs in New York State coordinate invasive species management,
recruit and train citizen volunteers, provide education and outreach, establish early detection
monitoring networks and implement direct eradication and control efforts. For more information,
Please join us for wildflower planting at Halle Ravine on Saturday, June 3rd, 10am to noon (link to directions). Families and non-gardeners are welcome to participate and to learn more about the value of our native plants and what they can do to bring in more birds and butterflies at home. Volunteers can assist with planting, watering, or removing non-native invasive species. We will have more than 200 plants on hand, all grown from locally collected seed and raised at the Armstrong Preserve and Education Center’s native plant nursery. Please bring a shovel or garden trowel if you have one. We will have some to share.
Our goal is to establish a native plant community in place of the thick stand of invasives that formerly dominated the entrance and pond edges. Wildflowers will help to fill space between the 200 young tree and shrub saplings that were planted during our Arbor Day Celebration last month, anchoring and shielding the soil while providing food for insects and birds. We hope to see these native plants become established and to begin to spread outside of their protective deer cages next year. Please email Krista if you would like to volunteer your gardening, photography, or other skills to this project on another date (email@example.com).
This volunteer event is part of our larger restoration efforts at Halle Ravine and is supported with funding from neighbors like you and by the New York State Conservation Partnership Program (NYSCPP) and New York’s Environmental Protection Fund. The NYSCPP in administered by the Land Trust Alliance, in coordination with the state Department of Environmental Conservation.
Native Plant-Insect Associations of Species Selected for Halle Ravine Restoration Planting
|Common name||Latin name||Bees||Butterflies||Moths||Other||Notable species|
|Blue-stem goldenrod||Solidago caesia||x||x|
|Cardinal Flower||Lobelia cardinalis||x||Ruby-throated hummingbird, Swallowtail butterflies|
|Climbing boneset||Mikania scandens||x||x||x|
|Columbine||Aquilegia canadensis||x||x||Ruby-throated hummingbird|
|Common boneset||Eupatorium perfoliatum||x||x||Baltimore checkerspot butterfly|
|Common heartleaf aster||Symphyotrichum cordifolium||x||American lady, Pearl crescent, Saddleback caterpillar|
|Flat topped aster||Doellingeria umbellate||x||American lady, Pearl crescent|
|Gray goldenrod||Solidago nemoralis||x||x||x|
|Great blue lobelia||Lobelia siphilitica||x|
|Horse mint||Monarda punctata||x|
|Tall meadow rue||Thalictrum pubescens||x|
|White wood aster||Eurybea divaricatus||x||American lady, Pearl crescent|
|Wild bergamot||Monarda fistulosa||x||x||x|
Pound Ridge’s Arbor Day Tree Planting and Celebration at Halle Ravine on April 28, 2017 was a grand success! Twenty-five people planted two hundred trees and shrubs in designated areas around the northern-most pond, which is visible from Trinity Pass near the Preserve entrance. We are grateful for their service in helping us to achieve our goal to enhance native understory forest in a 1.5 acre area that we just cleared of invasive Winged euonymus (aka Burningbush), with the long term plan of supporting native songbirds and other wildlife through habitat management.
We received funding for this work from the New York State Conservation Partnership Program (NYSCPP) and New York’s Environmental Protection Fund. The NYSCPP in administered by the Land Trust Alliance, in coordination with the state Department of Environmental Conservation. We also partnered with the Town of Pound Ridge Conservation Board, the Henry Morgenthau Nature Preserve, The Invasives Project-Pound Ridge, and our local troop of Girl Scouts for this event. Members of the Pound Ridge Garden Club generously donated a shuttle service to and from the Town Park, to alleviate the limited parking situation at Halle, and they helped to plant as well. Special guest Brad Gurr of Bartlett Tree Experts donated 100 oak and sycamore saplings and taught volunteers how to properly plant them. New York State Electric and Gas donated Eastern redbud saplings, and PRLC’s Prop Lab grew many others like Elderberry, Swamp rose, and Buttonbush.
Plantings were flagged temporarily for identification and watering, and most will be fenced from deer with either individual cages or perimeter fencing. We plan to add flowering herbaceous plants to these sites at our June 3 Volunteer Work Session to support pollinator insects and nectarivores. Please join us in supporting the restoration of Halle Ravine’s native forests by pitching in as a volunteer or making a donation to our Spring Fundraiser. This is a wonderful way to meet your neighbors and enjoy the woodlands we hold dear.
More pics coming soon!
Ten volunteers helped out at our April 1 work session held at the Richards Preserve. A team of four installed a water bar at the entrance to divert storm water from flowing into and eroding the trail system. Another team of four worked to create natural dams and obstructions that will capture sediment eroding from trails. Then, we all joined forces to remove Japanese barberry, an invasive shrub, from the entrance to the Preserve. We received grant funds from the Watershed Agricultural Council to clear barberry from one acre there this year. We also received funding from the Land Trust Alliance in support of our work to provide public access at Richards and to maintain the health of its habitats. Fortunately, the rest of this beautiful older-growth forest is free of invasives. Take the loop trail in either direction, and make sure to take in the reservoir view from the far end.