A major boom in domestic oil and gas production is under way, brought about by breakthrough refinements of a 1940s technology known as hydraulic fracturing, or “fracking.”

Hydraulic fracturing involves pumping water, sand, and some trace chemicals under high pressure into a completed wellbore to create fissures in relatively impermeable geologic formations such as shale. The fissures allow oil or natural gas to flow into the well. The sand props the fissures open, preventing the resealing of pathways. Combined with horizontal drilling at depths of one to more than two miles below the earth’s surface, hydraulic fracturing has unlocked vast stores …