Thursday, June 4, 2009


Blue Jay Barrens was pulverized by a meteor impact. Actually the impact took place before I named the area Blue Jay Barrens. About 300 million years before. The meteor drove everything before it deep into the earth, then gave way as all that battered rock rebounded to fill the temporary void. The result was an area about three miles across with rock of vastly different ages being close neighbors, rock layers tilting at all angles, radiating fault lines, and rock deformed by heat and compression.

One result was breccia, a sedimentary rock composed of cemented rock fragments. The breccia at Blue Jay Barrens is primarily limestone with a cementing agent of sphalerite, an ore of zinc that is often mined when found in sufficient quantity. Poor land management in the early 1900’s caused severe soil erosion to occur on large areas of Blue Jay Barrens. On the site pictured, the soil was completely lost and a large area of breccia was exposed. The sphalerite proved to be a poor cementing agent and breccia exposed to the elements quickly lost its cohesion and returned to its fragmented condition.

What we see today is almost inhospitable to plants. An Ash seed gives scale to this photograph. Freezing and thawing quickly change the breccia into fragments small enough to easily move with runoff water. This erosion usually occurs too rapidly to allow permanent colonization by plants.

Here you see an Eastern Red Cedar holding a small bit of soil on the breccia slope. Some of the cedars like the one here have been determined to be over 60 years old, but they still are less than six feet high.

Some Green Milkweed and Indiangrass have managed to become established on the lower part of this slope.

This Tulip Poplar seedling is off to a good start, but there is no way it can survive in this location. I doubt that it would have even gotten a start if it weren’t in the middle of a deer track. I think the deer compacted the soil enough for the seed to germinate and allowed for a protected environment in the slightly depressed area of the track.

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