Most people visit Target for home goods and clothing. But shoppers at this store are also treated to a glimpse of the Earth’s ancient past—if they know where to look.

In the early Mesozoic Era, the Connecticut Valley of central New England was volcanically active. Flows of lava rose up through fissures in the earth, spreading in massive molten seas across the land. 

Sometimes lava erupted in the deep waters of the numerous lakes and braided rivers that filled the ancient valley. The outer skin of this lava quickly cooled upon contact with water, but molten rock would continue to bulge it out from the inside, creating bubble-like “pillows” that eventually hardened into a dark, grainy stone called basalt.

Basalt pillows can be found in many places throughout the Connecticut Valley. One of the best and most accessible places to see them is the large, long rock-cut behind the Target store in Meriden, Connecticut. 

The pillows here are distinct and well-preserved. In some places, silt and sediment from the prehistoric lakebed pushed up between them, probably churned by billows of steam caused by the lava heating the water. The upper portion of the basalt formation is smoother, with fewer pillows. It is thought that at this level the lava had displaced enough water to create a long, open tunnel through which molten rock freely flowed.