The GVS is located between State Route 126 and the Little Miami River with a total area of approximately 304 acres. This area was formed during the Pleistocene Epoch (Ice Age), one of the most influential geological episodes in the cultural and economic development in Ohio. Towards the end of the Ice Age, as the glaciers that covered most of Ohio melted, water flowed carrying large amounts of sediment. This sediment or outwash, which now covers the southwestern third of the State, consists of rich agricultural soils and, in this case, sandy gravel filled the valleys of rivers, such as the Hocking, Great and Little Miami. These deposits are important economic resources that were laid down beyond the southern limit of glaciations. Grand Valley became part of one of the largest gravel mining areas in the United States.
These glaciated Ohio Basin-Alleghany Plateau areas, within the southwestern corner of Ohio would have likely been dominated historically by two biomes, defined as mixed mesophytic also containing riparian forests. The mixed mesophytic forests consisted of white oak, hickory, burr oak, black oak and chestnut. The American chestnut was a dominant canopy species, but was extirpated at the turn of the century by the introduced chestnut blight fungus. Riparian forest habitat, associated with stream and river banks, consisted of buckeye, black walnut, hackberry and sycamore. Large numbers of large sycamores were reduced as the area was cleared by early pioneer and later used as fuel for riverboats.
Today, the GVS is located in the area known as the Western Mesophytic Region and together with other mixed mesophytic forests, represent one of the most biologically diverse temperate regions of the world. Along with the multitude of canopy trees, these habitats support an abundance of understory ferns, fungi, perennial and annual herbaceous plants, shrubs, small trees and a diverse animal community. Although 95% of this type of habitat has been lost over the last 200 years, these forests continue to sustain the most diverse and endemic land snail, amphibian and herbaceous plant biotas in the United States and Canada.
Vast arrays of wildlife utilize riparian zones during their life cycles. Shade along the forest edge provides cooler water temperatures for fish and aquatic wildlife. These areas also filter water runoff and slow the rate of this runoff, which maintains stream flow during periods of low rainfall. The tree fall (debris and snags) provide habitat for fish and herpafauna that are part of the aquatic food chain. Upland species, not normally associated with riparian habitats may migrate to the water during the summer months. One important aspect of riparian forests is the travel corridors they provide for wildlife. The integrity of the riparian corridor associated with this site, along the Little Miami River, has been severely compromised, as a direct result of mining activities.
