Wednesday, May 27, 2015

Rock Point inventory: Brick's Brook

Next stop: Brick's Brook. Much of the sediment deposited atop the calcareous bedrock is lacustrine in origin (from a lake), deposited 11,000 years ago when the glaciers were retreating - melting - but still blocking drainage of the fresh water to the north through the St Lawrence seaway. Water pooled up in the Champlain Valley, the only outlet being the Hudson River valley to the south. The drainage point here is about 600', so Lake Champlain, which was known as Glacial Lake Vermont, was about 500' above where it is today.
The wet meadow, this is the "headwaters" of Brick's Brook

At the edge of the meadow, it starts to cut into the soils
About 25 down from previous photo, excessive erosion exposing roots of white pine
(which once upon a time was a fence line as witnessed by the barbed wire embedded in it)
The melt water draining off the mountains into the lake via the Winooski, Mississquoi, Lamoille, etc. would have been a muddy mess with glacial sediments. So Rock Point, which is adjacent to the lake, would have been a deep water environment, buried in alternating layers of silts and clays each year when the lake froze over. These silts and clays drain very poorly, accounting for  the wet meadows and depressions found scattered over the land.

Further still downstream. Slopes of banks still steep. 
Once the glaciers retreated far enough to the north, finally opening up the St Lawrence seaway, water exploded out of the Champlain Valley, draining in a matter of hours or days down to an elevation of 300'. At that point, because the glaciers were so heavy, their weight had actually depressed the entire northern part of the continent - much like a large putting all your passengers at the stern of a flexible boat - by about 300' in this area. The glacial lake gradually grew saltier and saltier as water from the ocean filtered into Champlain Valley. The rivers continued flowing into the body of water; the Winooski River delta's edge terminated at Rock Point, depositing patchy layers of sand atop the lacustrine silts and clays.

Soil map generated by Web Soil Survey:
This sandier stuff erodes rather easily. Brick's Brook, which is only about 600m in length, starts as a trickle in the Old Pasture. A small bridge passes over the small notch carved into the clay soils. At the edge of the meadow, soils are much sandier and within 50m, the notch is a deep valley with steep slopes. Eventually the stream eroded down below the sandier soils, exposing silts and clays. Because these smaller soil particles are more difficult to erode, the valley widens rather than cutting further down. Towards the lower end of the stream the slope of stream is much gentler, water does not drain as well, and the course of the stream begins to meander, with water pooling up much more. In this section there are often green frogs and wood frogs.

Near the bottom, mellow grade to the brook and shallow slope to the banks due to erosion over time
High water table wreaking havoc on the hemlcoks and yellow birches
Species list is not complete (there are 5 different plants I need flowers to key out):

Maple, redAcer rubrumAceraceae (Maple)
Maple, sugarAcer saccharumAceraceae (Maple)
Ivy, poisonToxicodendron radicansAnacardiaceae (Cashew)
Birch, yellowBetula allegheniensisBetulaceae (Birch)
Viburnum, maple-leafViburnum acerifoliumCaprifoliaceae (Honeysuckle)
Honeysuckle, ??Lonicera ??*Caprifoliaceae (Honeysuckle)
Bittersweet, orientalCelastrus ????*Celastraceae (Bittersweet)
Dogwood, red-osierCornus sericeaCornaceae (Dogwood)
Witch-hazel, AmericanHamamelis virginianaHamamelidaceae (Witch-hazel)
Basswood, AmericanTilia americanaMalvaceae (Mallow)
Ash, greenFraxinus pennsylvanicaOleaceae (Olive)
Hemlock, EasternTsuga canadensisPinaceae (Pine)
Buckthorn, commonRhamnus cathartica*Rhamnaceae (Buckthorn)
Buckthorn, glossyFrangula alnifolia*Rhamnaceae (Buckthorn)
Blackberry, commonRubus allegheniensisRosaceae (Rose)
Cherry, blackPrunus serotinaRosaceae (Rose)
Raspberry, blackRubus occidentalisRosaceae (Rose)
Rose, multi-floraRosa multiflora*Rosaceae (Rose)
ThimbleberryRubus odoratusRosaceae (Rose)
Aspen, quakingPopulus tremuloidesSalicaceae (Willow)
GRAPE sp.Vitaceae (Grape)
Virginia creeperParthenocissus quinquefoliaVitaceae (Grape)
Jack-in-the-pulpitArisaema sp.Araceae (Arum)
Jewelweed, spottedImpatiens capensisBalsaminaceae (Touch-me-not)
Solomon's seal, falseSmilacina racemosaLiliaceae (Lily)
Crowfoot, small flowerRanunculus abortivusRanunculaceae (Buttercup)
Lily, troutErythronium americanumLiliaceae (Lily)
Skunk cabbageSymplocarpus foetidusAraceae (Arum)
DandelionTaraxacum officinalis*Asteraceae (Aster)
Meadow rue, earlyThalictrum dioicumRanunculaceae (Buttercup)
Baneberry, redActaea rubraRanunculaceae (Buttercup)
Nightshade, enchantersCircaea spOnagraceae (Evening primrose)
MiterwortMitella diphyllaSaxifragaceae (Saxifrage)
Nettle, woodLaportea canadensisUrticaceae (Nettles)
Nightshade, deadlySolanum dulcamara*Solanaceae
SpeedwellVeronica spScrophulariaceae (Figwort)
Fern, ladyAthyrium filix-feminaAthyriaceae
Fern, brackenPteridium aquilinumDennstaedtiaceae (Bracken)
Wood fern, spinuloseDryopteris carthusianaDryopteridaceae (Wood fern)
Wood fern, intermediateDryopteris intermediaDryopteridaceae (Wood fern)
Horsetail, woodEquisetum sylvaticumEquisetaceae (Horsetail)
Horsetail, meadowEquisetum pratenseEquisetaceae (Horsetail)
Fern, sensitiveOnoclea sensibilisOnocleaceae (Sensitive Fern)
Fern, ostrichMatteuccia struthiopterisOnocleaceae (Sensitive Fern)
Fern, cinnamonOsmunda cinnamomeaOsmundaceae (Royal fern)
Fern, interruptedOsmunda interruptaOsmundaceae (Royal fern)
Fern, maiden hairAdiantum pedatumPteridaceae (Maidenhair)
Fern, New YorkThelypteris noveboracensisThelypteridaceae (Marsh)

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