Background
The Blasted Heath was an area that once existed a few miles outside the town of Arkham, Massachusetts.
For much of the last century, the Blasted Heath had been covered over by the Arkham town reservoir. The general population of Arkham was unaware of this fact.
The meteor
The meteor falls to Earth.
In the late 19th Century, a meteor fell from the sky and landed on the farm of a family named Gardner (a husband, wife, and three sons).
Scientists from Miskatonic University travelled out to the Gardner farm to investigate said meteor, but were unable to learn much about it. The meteor soon dissolved away into nothing, and no trace of it was left.
The strange fate of the Gardner family
However, over the next year, strange events happened on the Gardner farm. The fruit went bad almost overnight, the animals began to die off, and the trees and bushes in the whole area withered away. As for the Gardner family themselves, they just vanished, all five of them. Some said that something that came from that meteor consumed them. However, the mystery of their fate was never really determined or solved.
The Blasted Heath is born
The Gardner farm and the surrounding area became a desolate and dead area, which the locals at the time called the Blasted Heath. It was said that it actually glowed in the dark with a strange, alien light. In time, none of the locals would go near the area.
Covered over
In the early 1930's, the town of Arkham built a reservoir which covered over the Blasted Heath. Therefore, whatever secrets the Blasted Heath may have hidden were now out of reach.
Hannah uncovers the story of The Blasted Heath
in 2015, Hannah Webster began investigating many of the strange events that had occurred in and around Arkham. The Blasted Heath being one of them The information she uncovered ended up being part of the article she submitted to, and had published by, the Arkham Gazette.
The illness and end of the Blasted Heath
In early 2016, a mysterious illness swept through Arkham and began slowly affecting the town population (including Staci Clarke). Rex and Hannah soon discovered that the illness was tied into the Blasted Heath. It turned out that the meteor that had landed on the Gardner farm in the late 19th Century had originated on Yuggoth. It had been a piece of volcanic debris that had been hurled into space by an eruption from one of Yuggoth's many volcanoes and had eventually fallen to Earth.
Over the decades that the Blasted Heath had been covered over by the town reservoir, the Blasted Heath had continued to expand. The contamination became so much that the water filtration systems were no longer able to contain it, and it had begun to seep into Arkham's water supply.
Rex and Hannah soon realized that the cure could be found on Yuggoth. Rex and Hannah thus returned to the dark planet and were successfully able to procure the cure from the Mi-go. The cure had been a tablet. Upon their return to Earth. Rex and Hannah dropped said tablet into the reservoir, it quickly neutralized the Blasted Heath and then successfully cured all the affected townspeople.
As of these events, the Blasted Heath is no more.
References
The Colour Out Of Space by H.P. Lovecraft
Rex and Hannah Chronicles Story No. 35: The Legacy Of Tempest Mountain
Rex and Hannah Chronicles Story No. 36: Arkham Oddities
Rex and Hannah Chronicles Story No. 41: Outbreak