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Limestone Erratics
Description
There is no limestone bedrock in the Forest, but occasionally you can find a limestone boulder that was left behind by the glaciers. These probably originated nearby, there are layers of limestone rock on Schunemunk and in the Shawangunks. These limestone erratics have a distinctive flora similar to that found in areas with limestone bedrock. They are also easy to find, especially when the trees have lost their leaves, because they are always covered by a green carpet of moss.
Selected Plants
Shrubs
- Ribes rotundifolia (Gooseberry)
Herbs
- Anomodon rostratus (Moss)
- Asplenium rhizophyllum (Walking fern)
- Asplenium trichomanes (Maidenhair spleenwort)
- Mitella diphylla (Twinleaf)
- Asarum canadense (Wild ginger)
- Arabis lyrata (Rock cress)
Occurrence
Limestone erratic along Mountain Road
Limestone erratics occur sporadically in the Forest. There is one between the road and the stream along Mountain Road between the Science Center and the Upper Reservoir. Another large erratic occurs in the cove along Canterbury brook.
Ecology
Areas with limestone bedrock support unique and interesting floras. Our erratics are a miniature version of these areas, supporting a suite of plants not otherwise found in the Forest. Most of the bedrock in the Forest is gneiss or granite which give rise to acidic, nutrient poor soils. Soils on limestone are basic and are usually richer in nutrients.
Sometimes, limestone-loving plants can also be found growing near old cement walls, foundations, and dams.
For general references see the reference page.
Photos: Kerry Barringer