Avondale Park, like much of Jones Valley, falls within the Southern Limestone/Dolomite Valleys and Low Rolling Hills level IV ecoregion. This is a landscape where dolostone and limestone lie just below the surface. These rock formations yield numerous springs, sinkholes, and caverns – a landscape known as karst.
The pre-settlement landscape of this ecoregion’s valleys supported lush forests with many types of trees, many of which can be found in the wooded portions of the park. Due to the moist nature of the valley’s ecosystems, wildfires were rare and occurred only during severe droughts. The bedrock beneath the floor of these valleys weathered into alkaline soils that supported agriculture when the region was first settled.
A few low hills rise from the valley floors of this ecoregion. Most are composed of harder rocks, especially chert and sandstone, which resist erosion more than the limestone and dolostone. In pre-settlement times, the hills provided habitats for plants and animals suited to dryer ecosystems. Wildfires started by lightning probably burned these hills about once every decade, but no one knows for sure.
This level IV ecoregion, which stretches from central Alabama to New York State, is nested within the Ridge and Valley level III ecoregion, an area dominated by linear ridges and intervening valleys. The diverse topography and geology support many ecosystems and, thus, many species.
–R. Scot Duncan