Early geologists first mapped Maine’s landscape in 1837 and later generations did bedrock surveys and traced the state’s history back half a billion years.
Today, the Maine Geological Survey has a varied mission spanning everything from groundwater education and erosion control to sea level rise and research. Maine state geologist Robert Marvinney joined the agency in 1987, as the state agency was wrapping up a large-scale mapping of major aquifers that 70 municipal drinking water systems now use, and he said he’s never been bored.
“There are a lot of detailed investigations that remain to be done,” Marvinney said of the understanding of Maine’s rock systems. “In many places, it was very brief reconnaissance that filled in blank spots of that map. Even the general geology shown on that map may be incorrect.”
The Geological Survey is currently working on mapping unidentified bedrock in the town of Yarmouth, along with several projects in northern Maine, which “has not been covered quite well” since the last mapping in 1985, Marvinney said. Marvinney, a New Jersey native, helped map parts of northwestern Maine as a graduate student in Syracuse with his professor Gary Boone, a Presque Isle native who returned to the Star City in retirement.
In northern Maine, teams are mapping bedrock around Round Mountain and Norway Bluff, and in some places, “we’re finding that 1985 map doesn’t hold up,” Marvinney said.
Around Norway Bluff, the former site of a historic fire tower, the research has found more layers of volcanic chert that were likely part of quarry sources of flint used by Native Americans over thousands of years.
In 2011, the construction of a radio tower at Norway Bluff, following the removal of the fire tower, led to the destruction of several of those quarries, Marvinney said. A contractor who was supposed to rely on a helicopter and was apparently not aware of the ancient sites bulldozed through them following the path of old woods roads. The Maine Historic Preservation Commission ended up settling with the company.
More chert layers and some other quarries have been found, and been referred to the preservation commission, which oversees archaeological sites, Marvinney said.
Further north in Aroostook County, the Geological Survey contracted with University of Maine Presque Isle geologist Chunzeng Wang to document the bedrock at Chandler Mountain. There they’ve found volcanic sulfide deposits similar to those around Bald Mountain, where several companies in past three decades have expressed interest but never followed through on a mine for copper, gold and other metals.
“They had been known since the ‘70s,” Marvinney said of the metal-bearing rocks found around Chandler Mountain. “But [Wang] has found more extensive minerals than was thought.” These formations are relatively shallow on the large scale, at around 100 feet below the ground, and may be the sources of “gold nuggets” — not actual gold but copper pyrite — that some loggers in the North Maine Woods have reported.
Copper, gold, silver and other metals that come with volcanic sulfide rocks are “probably in many undiscovered deposits” in different parts of Maine, Marvinney said.
Looking for minerals that can be mined is not the primary objective of the studies and they only note the location and the information gleaned from studying natural and artificial exposures from road construction, Marvinney said, adding there is no underground drilling.
At the same time, Marvinney is a supporter of mining in Maine and was the only person to testify in favor of the Department of Environmental Protection’s third iteration of proposed metal mining rules at a public hearing in September.
“It’s important to have this discussion,” he said, of the debate over the mining rules. “My role has been to inform people about the nature of volcanic rocks and to remind people that we used metals in our everyday lives. Modern society wouldn’t exist without metals. Even though we can recycle metals, that volume is not sufficient to meet the demands of modern society. Mining is going to occur, and in many parts of the world there’s a lot of environmental degradation that happens. We need to find a way to address the environmental concerns and allow mining to go forward.”
Some Maine environmental advocates argue that most if not all of the state’s volcanic sulfide deposits, including Bald Mountain, are too concentrated in naturally-occurring toxins and acidic rocks to be mined safely, especially considering Maine’s water-rich landscape and climate.
Marvinney said he’s not sure about whether Bald Mountain can be mined safely. “I don’t think there’s been enough analysis to know how it might be mined economically. It would depend on the details of how wastes are managed,” Marvinney said.
In the future, higher metal prices could also make it viable to avoid destructive open pit mines through underground mines that reduce waste, Marvinney said.
He along with DEP staff and Board of Environmental Protection member Tom Easler travelled to Michigan to visit a new underground copper and nickel mine in the Upper Peninsula region, and concluded that the underground mine “can be done in a responsible way in the northern temperate climate.”
If the DEP’s proposed rules are adopted by the legislature, Marvinney said it would likely take a decade for an application to turn into an operational mine, and only a small portion of Maine would likely be ideal for mines.
“I’d be surprised if 1 percent of deposits could be large enough or be developed in a way that’s environmentally sound,” Marvinney said.
