Trail Section 16 - Falls Lake Trail Geologic Guide

 

Geologic Map Trail Section 16-21

Geologic information by Edward F. Stoddard (in Bold Text).

Mileage and Trail section descriptions from Mark Edelstein with updates from March – April 2011.

 

Section 16 (Cheek Road to Hereford Road)

4.7 – After approximately 70 yd, cross the road to reenter woods.

4.9 – Cross an open area after trail curves to the R. Soon pass by the edge of a field.

16-A:  Occasional chunks of diabase are visible along here.

5.1 – Lake views become available, R.

16-B:  Here, off to the right toward the lake, is an excellent big bouldery outcrop of a diabase dike.  If you go to investigate it, you will find the effects of jointing in three directions, which has effectively broken the solid rock into large cubes or rectangles.  Then, as a result of water gaining access along these cracks, the cracks grew wider by freeze-thaw cycles, and chemical weathering has caused the corners and edges of the cubes to become somewhat rounded.  This is the process of spheroidal weathering, which eventually results in the round boulders we have been seeing (Figure 16-B).

Another thing to consider here is that, if you could follow this dike down into the earth below the water table, the cracks in the rock would be filled with water.  In fact, this characteristic causes diabase dikes to be a very good source of ground water in the Triassic basin.  The surrounding sandstones and other sedimentary rocks are poor sources, so if you drill a water well in the Triassic area, try to find a diabase dike.

5.4 – Pass through another open area with a nice lake view, R.

5.6 mi – Reach Hereford Road. To reach the next section, turn R to walk along the road’s shoulder.

16-C:  As you walk across the causeway, you will notice that that the inlet becomes constricted as it enters the lake (Figure 16-C).  This is because of the much harder diabase bedrock at the constriction, while softer sandstone is the bedrock closer to the causeway, resulting in a wider inlet here.

End of Trail Section 16

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