Dye tracing is a tool commonly used by geologists to monitor how water moves through the ground. The above picture is from a study the Arkansas Geological Survey conducted for local residents in Izard County, Arkansas. Dye was added to water to track the path of farm runoff entering the groundwater through a sinkhole.
The test consists of pouring brightly colored, non-toxic dye into water before it enters the ground. Charcoal packets, capable of detecting low concentrations of the dye, are placed in nearby springs and wells. After some time has passed, the packets are analyzed to see where the water and dye travelled after soaking into the ground.
Because the earth is often their laboratory, geoscientists have to come up with creative approaches to studying inaccessible places. Besides, there’s just something satisfying about dyeing large quantities of water bright colors.