Nature trail guide—Greenbank’s Hollow Historic Park

By Dave Houston

A field-use trail guide for the Greenbank’s Hol­low Nature Trail is avail­able at the His­tor­i­cal Park. How­ev­er, the fol­low­ing descrip­tion con­tains added detail and pho­tos (click on pho­tos and fig­ures to enlarge). Even so, this is a work in progress as more infor­ma­tion will be includ­ed as it becomes available.

Exam­ples of things to come:

• Lists, descrip­tions and pho­tos where appro­pri­ate, of plants and ani­mals found here along the trail or sur­round­ing area, includ­ing birds, mam­mals, amphib­ians and  rep­tiles, and insects, as well as oth­er bio­ta such as fun­gi and archaea.
• Detailed descrip­tions and loca­tion (map) of the soils present here, includ­ing their suit­abil­i­ty for sup­port­ing plants, etc.
• Infor­ma­tion relat­ed to Joe’s Brook includ­ing sea­son­al flow data, water chem­istry, suit­abil­i­ty for fish habi­tat, and his­tor­i­cal use of water power.
• Addi­tion­al geo­log­i­cal details con­cern­ing the ori­gin, for­ma­tion and char­ac­ter­is­tics of the bedrock beneath the Park.
• The influ­ence of the bedrock and the last glacia­tion on the shape of our land­scape and the soils that blan­ket it.

THE SETTING:

Geology

The bedrock under­ly­ing this area con­sists pri­mar­i­ly of the Waits Riv­er For­ma­tion,

a meta­mor­phic rock com­plex formed dur­ing the Devon­ian Peri­od (410 to 360 mil­lion years ago). This was a very active peri­od geo­log­i­cal­ly. Land mass­es in the lapetan Marine Basin (pre­cur­sor to the Atlantic Ocean) gath­ered into super­con­ti­nents, squeez­ing sed­i­ments from the ocean floor between them and meta­mor­phos­ing those sed­i­ments from the pres­sure as the land­mass­es collided.

Before this col­li­sion, high­lands along the shore­lines erod­ed, yield­ing huge vol­umes of sed­i­ments that were deposit­ed in vast near­by low­lands and shal­low seas. Some of these sed­i­ments, togeth­er with deposits of lime-rich sea organ­isms, became the meta­mor­phic rocks of the Waits Riv­er For­ma­tion when they were sub­ject­ed to repeat­ed defor­ma­tion and meta­mor­phism dur­ing clo­sure of the lapetan basin and col­li­sion of the land­mass­es that would some­day be known as Europe and America.

Our com­plex bedrock, there­fore, has a com­plex his­to­ry:  Seabed deposits, com­prised of both vol­canic and car­bon­ate sed­i­ments, most like­ly fine quartz sand with clay part­ings, silts and clay-rich muds, became sed­i­men­ta­ry rock beds of lime­stone and shale. These rocks, in turn, were meta­mor­phosed to become the dark mar­bles, phyl­lite, and mica schists char­ac­ter­is­tic of the Waits Riv­er For­ma­tion. These rock types interbed and inter­grade and may con­tain oth­er min­er­als depend­ing on the degree of metamorphism.

This rock com­plex, exam­ples of which can be seen exposed as the bot­tom and south shore of Joe’s Brook near the sawmill and grist­mill sites, is the basis of the fer­tile, non-acidic agri­cul­tur­al soils of east­ern Vermont.

Soils

Glacial activ­i­ty and time have blan­ket­ed this lit­tle park with a rel­a­tive­ly com­plex mosa­ic of soils. These range from poor­ly- drained Cabot, to mod­er­ate­ly well-drained Buck­land, to well-drained Dum­mer­ston. The soils appear rel­a­tive­ly deep, with pH (acid­i­ty) lev­els rang­ing from 5.1 to 7.3 (7.0 is neu­tral), ide­al for north­ern hard­woods (birch, beech, maple) in the dri­er areas (Buck­land, and Dum­mer­ston) and cedar where soils are wet­ter (Cabot). These soils are all high­ly erodible.

Land Use History

In the ear­ly- to mid- 1800’s most of the park and sur­round­ing area was cleared. Areas too wet, steep, or stony for agri­cul­tur­al uses were retained as wood­lots. Lat­er, as lands sur­round­ing res­i­dences and mills were aban­doned from active agri­cul­ture, the inex­orable nat­ur­al process of plant suc­ces­sion began and, even­tu­al­ly, much of the park­land ear­li­er cleared for farms and res­i­dences became occu­pied, once again, by for­est shrubs and trees. This Nature Trail pass­es through such ear­ly stage for­est and “old” wood­lot areas.

THE NATURE TRAIL

The trail is described below as it descends down a steep slope to brook lev­el. It is mod­er­ate in dif­fi­cul­ty (many steps and switch­backs), and one can choose to descend or ascend -–it is delight­ful either way. For a print­able hard copy of the map click this link: map and leg­end.

Begin­ning at the School House (Site 8), the trail pass­es east through large white pines, Pinus strobus L., (1)  that seed­ed in on the for­mer­ly open land around the school and the adja­cent “Adams res­i­dence” (Site 9). Some of these trees are now declin­ing (note their thin, small crowns). It is very like­ly that parts of this site are a bit too wet to sup­port mature white pine. Indeed, the lit­tle “sedge mead­ow” (2) between the school and the Adams res­i­dence denotes a site quite wet for parts of the year and prob­a­bly delin­eates where the Cabot soils begin to appear. Near the edge of the steep slope, where soils are bet­ter- drained, the pines are big­ger and in good health.

Near where the trail turns to start down the steep, south-fac­ing slope some large black cher­ry, Prunus seroti­na Ehrh., (3) trees also bear wit­ness that the land here was once open. Like white pine, this “shade-intol­er­ant” species need­ed full sun­light to become estab­lished. Before turn­ing and head­ing down, note where, just ahead, the land drops sharply to a ravine (4) being cre­at­ed by an inter­mit­tent stream cut­ting down through this high­ly erodi­ble soil on its way to Joe’s Brook.

The trail descends through a dense stand of north­ern white cedar, Thu­ja occi­den­tal­is L., (5).

A blow-down here has cre­at­ed a jack­straw tan­gle of cedar trees. This species char­ac­ter­is­ti­cal­ly occurs on organ­ic soils in “moist, cool, nutrient–rich sites near streams or oth­er drainage ways” and on “cal­care­ous min­er­al soils”—a per­fect descrip­tion of this site. In the blow-down area, where light now reach­es the ground, saplings of black cher­ry, white ash, Frax­i­nus amer­i­cana L., and sug­ar maple, Acer sac­cha­rum Marsh., are mak­ing their way up through the tangle.

Fur­ther downs­lope, light-lov­ing species become more abun­dant where an open­ing (6), cre­at­ed by an ear­li­er tree har­vest, allows sun­light to pen­e­trate the under­sto­ry of the slope- side. Along the edge of this open­ing black cher­ry, paper birch, Betu­la papyrifera Marsh., and moun­tain ash, Sor­bus amer­i­cana Marsh., become more numer­ous. Clumps of alder, Alnus spp., and an occa­sion­al wil­low, Sal­ix spp., occur in the low­er, wet­ter areas along with dense ground cov­ers of ferns, milk­weed, gold­en­rods and grape. Large rem­nant ash, cedar, and cher­ry trees are scat­tered in and around the opening.

After a short swing back onto the cedar slope, the trail descends through an arch cre­at­ed by a storm-bro­ken cher­ry. Note the “new” trees that have arisen fol­low­ing the “acci­dent” as well as the storm-bent old­er cher­ry nearby.

Just beyond, the first of a series of board­walk bridges (7) span small “ravines-in-the-mak­ing” where water floods down­hill in times of heavy rains. Here, moss-cov­ered cedar logs and abun­dant  ash and moun­tain maple, Acer spi­ca­tum Lam., attest to the moist­ness of this cool bot­tom­land. Large cedar stumps and downed logs still present here, long after trees were cut, tes­ti­fy to the high decay resis­tance of this species.

 

Just beyond the bridge, a spur trail turns left (south) and then up and along a nar­row knob to its end. Cool and moist, this site is ide­al for bal­sam fir, Abies bal­samea L., sug­ar maple, cedar and, espe­cial­ly, for yel­low birch, Betu­la alleghanien­sis Brit­ton, that makes its first trail appear­ance here (8). This side spur, kept “more nat­ur­al” than the main trail, affords a won­der­ful oppor­tu­ni­ty for soli­tude and enjoy­ment of the sight and sounds of the brook below.

 

 

 

A sit­ting bench at trail’s end (9) rests with­in a ground cov­er patch of Cana­da yew, Taxus canaden­sis Marsh.,  sur­round­ed by tall cedars and old birch. While not espe­cial­ly com­mon, the patch of yew here is quite exten­sive as it spills down over the edges of the knob. This unique knob most like­ly exists because of its under­ly­ing bedrock—a bit of which can be seen from the main trail below.

 

The main trail con­tin­ues over the next board­walk bridges. Note the huge trunks of old trees that have fall­en down­hill on the right (10). Big trees become tar­gets for wind and ice storms and are espe­cial­ly vul­ner­a­ble on steep slopes when soils become saturated.

Con­tin­ue through the “fall­en tree zone” to the sawmill (Site 11) where a short side trail leads down to the north shore of Joe’s Brook.

Here, excel­lent exam­ples of the Waits Riv­er For­ma­tion rocks are exposed as ledges of both the stream bot­tom and banks of the south shore­side (11). The brown, weath­ered, crus­tose sur­faces and the inclu­sions of quartzite and schists are char­ac­ter­is­tics of these rocks.

In times of low water, radi­at­ing pat­terns of vary­ing sizes can be seen on some worn sur­faces. These are crys­tals of min­er­als that were formed dur­ing meta­mor­phism. Note that some of these min­er­als are more resis­tant to ero­sion and weath­er­ing and stand out in relief from the soft­er, more cal­care­ous coun­try rock.

The trail ends as it enters the mead­ow just past the grist­mill (Site 10). Here, the force­ful, flow­ing water, long freed from the task of turn­ing mill­stones, works relent­less­ly to remove the mill’s foun­da­tions and reclaim its stream banks.