{"id":21602,"date":"2017-11-01T00:01:49","date_gmt":"2017-11-01T07:01:49","guid":{"rendered":"http:\/\/live-hakamagwp.pantheonsite.io\/?post_type=custom_features&p=21602"},"modified":"2023-03-08T11:57:06","modified_gmt":"2023-03-08T19:57:06","slug":"scientist-who-reads-lost-history-mud","status":"publish","type":"custom_features","link":"https:\/\/hakaimagazine.com\/features\/scientist-who-reads-lost-history-mud\/","title":{"rendered":"The Scientist Who Reads a Lost History in the Mud"},"content":{"rendered":"

\u201cLet\u2019s drive to Soldiers Delight,\u201d says Grace Brush. So out we go up Baltimore\u2019s treeless Reisterstown Road and down county back roads through Maryland\u2019s thick summer green. Suddenly, we\u2019re among hills with sparse grass and a slightly scrubby forest. This is Soldiers Delight Natural Environment Area, a serpentine barren that looks out of place in this lush country. It\u2019s a peculiar landscape and Brush is a paleoecologist, an expert in the history of landscapes. She views landscapes the way physicians view bodies: systems of interconnected parts, changing with time, resilient until they\u2019re not.<\/p>\n

Brush is 86 years old, so we stump cautiously along paths that are interrupted by corrugated pavements of silvery gray-green serpentine rock. It\u2019s a little hard for her to navigate, though she\u2019s paying less attention to her balance than to the rock itself. Serpentine was born directly from the Earth\u2019s mantle and when it weathers, she says, \u201cyou don\u2019t get much soil.\u201d The dirt that does weather out is shallow, low in plant nutrients, and doesn\u2019t hold water, so few tree species grow here. Brush points out what does grow\u2014blackjack and post oak, sassafras, greenbrier, grasses, and ferns\u2014and stops to examine the individuals. Our progress is slow but relentless.<\/p>\n

In the early 1800s, Soldiers Delight\u2019s serpentine was found to contain chromite, and this area and the nearby barrens were mined; for a while, Baltimore County was the world\u2019s largest supplier of chrome. Brush walks me to the open-pit Choate Mine, talking about how the mines and later the invasive suburbs meant that natural wildfires were quickly stamped out. But \u201cgrasslands need fires,\u201d she adds, and without fires, \u201cVirginia pine moved in.\u201d Beginning in the 1960s, a group of ecologically minded citizens lobbied to protect the area, cut the pines, and set up controlled burns. The serpentine barrens are now returning to their normal abnormality, which includes many rare wildflowers.<\/p>\n

Brush takes a wildflower identification book out of her jacket and stops to identify tiny flowers on thready plants, though we\u2019re a little early in the wildflower season. \u201cWe\u2019ll come back,\u201d she says. We came in the first place because Brush wanted to show me what she means by \u201clandscape,\u201d that is, space plus time, cause and result, from the rock to the dirt to the plants; birth, destruction, restoration.<\/p>\n

\n

Brush\u2019s true love and deepest expertise is in an entirely different landscape, that of the Chesapeake Bay. She was 41 years old and living in Baltimore about the time the bay was found to be dying. The Chesapeake is an estuary, the world\u2019s third largest, created in part by 150 rivers that drain 166,000 square kilometers and flow into the Atlantic Ocean. Thus, the bay is a mixture of fresh and salt water. It has 3,600 species of plants and animals, and its watershed area has 18.1 million humans. Its fisheries are worth billions of dollars and they employ tens of thousands of people.<\/p>\n

\"Early<\/a>

Early European settlers were struck by the abundance of oysters in the Chesapeake Bay, noting that they \u201clay as thicke as stones,\u201d and for centuries fishermen raked in large catches. But in the 1970s, the catches began declining in an alarming way. Photo by Granger Historical Picture Archive\/Alamy Stock Photo<\/p><\/div>\n

But in the early 1970s, the Chesapeake was rapidly losing oxygen, fish, oysters, and plants. The loss coincided with the growth of the environmental movement, and the newly created US Environmental Protection Agency (EPA) began funding scientists, including Brush, to figure out what was wrong with the Chesapeake and how to fix it.<\/p>\n

Ecological landscapes are notoriously complex, with many variables and an unknown number of unknown connections: \u201cWhen we try to pick out anything by itself,\u201d the famous naturalist John Muir once wrote, \u201cwe find it hitched to everything else in the Universe.\u201d Ecologists wanting to restore a broken landscape must deal with not only that complexity, but also with shifting baselines. That is, ecologies change with time, shifting naturally through stability to instability to the next stability. So one of the big questions facing ecologists is: to which stability should restoration return?<\/p>\n

Brush\u2019s approach to the problem was meticulous, elegant, and obvious: before fixing the Chesapeake, figure out the long history of its shifts and changes. With colleagues and generations of graduate and undergraduate students (whom she carefully credits), she took core samples of the bay\u2019s sediments, the oldest of which date back a little over 14,000 years. In the sediments, she counted pollen grains and other tiny indicators of what was growing on the land and what was living in the water, and assembled an ecological history of the bay.<\/p>\n

The project took decades of detailed work. For the past 40 years, Brush has thought through the complex living arrangements of the bay landscape, identifying every variable and measuring each one to see how the Chesapeake got from then to now. \u201cGracie chasing down the past,\u201d says Walter Boynton, an ecologist at the University of Maryland. Core by core, variable by variable, methodically, precisely, Brush pieced together evidence of the relationships between failing fisheries, river sediment, the sudden disappearance of underwater grasses, and a bay with a serious chemical imbalance.<\/p>\n

\"Through<\/a>

Through more than 30 years of coring and analysis, Brush\u2019s research detailed the harmful effects of deforestation, agriculture, and chemical fertilizers on the ecology of the Chesapeake Bay and its species. Photo by David Harp<\/p><\/div>\n

\u201cBrush\u2019s work was foundational,\u201d says Rich Batiuk, the EPA\u2019s associate director for science, analysis, and implementation.<\/p>\n

And she accomplished much of this without tenure and the usual net of academic securities. Some universities gave her not contracts or salaries, but access to work space and graduate students. She funded most of her work with grants, one after another, never sure where the next one would come from. She got her first tenured position at Johns Hopkins University in 1990, when she was 59, an age at which most scientists are past their prime. Her most recent scientific papers were published this year. One of her former graduate students, Daniel Bain, a geologist at the University of Pittsburgh, says \u201cshe\u2019s tough as heck.\u201d<\/p>\n

\n

Grace Somers Brush is of medium height. She has curly, sandy-gray hair, doesn\u2019t stand quite as straight as she used to, and looks like she\u2019s nobody in particular. If you\u2019re talking mundanities, she\u2019s polite but her attention tends to drift. If you want to know about the silt piling up in the Susquehanna behind the Conowingo Dam, she snaps to, knows exactly what she thinks, says so, and backs it up with evidence.<\/p>\n

Brush grew up in rural Nova Scotia, going to a tiny country school with a monthly delivery of books, all of which she read. She spent a lot of time outdoors in the woods and at a nearby lake. \u201cNova Scotia was totally glaciated,\u201d she says, so her outdoors was a postglacial landscape of bogs, lakes, rocky coasts, and sandy beaches, as well as a northern forest with conifers, maples, hemlocks, and aspens. When she was 13, her only option for continuing education was a boarding school in Antigonish, 40 kilometers from her home; she stayed in the small town to attend St. Francis Xavier University. One of her classes took a field trip to an outcrop called Joggins Fossil Cliffs, a slice through 300 million years\u2019 worth of rock. Some layers revealed fossilized tree ferns that could have grown only in the tropics. That landscape would have looked nothing like the postglacial land she was standing on. Why were landscapes in the same place so different at different times, she later wondered?<\/p>\n

In 1956, she finished a PhD dissertation at Harvard University on the ancient pollen from tropical and semitropical plants preserved in 200-plus-million-year-old fossils from the American Midwest. Eventually, she became seriously interested in landscapes. They are profoundly unlike, and each one changes profoundly with time. How does that happen?<\/p>\n

By 1969, after a number of short but productive stays in various universities, Brush moved to Baltimore for good, just in time for the discovery that the Chesapeake Bay was sick.<\/p>\n

\n

Some 35 million years ago, when the mid-Atlantic coast was even swampier, hotter, and more humid than it is now, a comet or asteroid three to five kilometers in diameter hit the region. It left a crater twice the size of Rhode Island. In time, rivers from the Appalachians began flowing northeast and southeast toward the crater. And about 10,000 years ago, after the last ice age ended, glaciers melted and the sea level rose, flooding the crater and up into the rivers; the biggest river valley, the Susquehanna, became the Chesapeake Bay.<\/p>\n

\"map<\/a>

Satellite image by NASA, illustration by Mark Garrison<\/p><\/div>\n

Indigenous Americans made a good living for thousands of years along its shores, hunting and fishing. And early Europeans were much taken with the region. In the early 1600s, Captain John Smith called the Chesapeake \u201ca very goodly bay.\u201d The land around it, he added, was pleasant: \u201covergrowne with wood,\u201d \u201cwell-watered,\u201d and \u201cthe vallies very fertill.\u201d In the water were blue crabs, oysters that \u201clay as thicke as stones,\u201d and \u201can aboundance of fish, lying so thicke with their heads above the water.\u201d The rivers were large and navigable, and, Smith concluded, \u201cheaven and earth never agreed better to frame a place for man\u2019s habitation.\u201d<\/p>\n

Over the next few centuries, the land around the very goodly bay was fished, farmed, urbanized, and industrialized. By the late 1800s, the forests, which had once covered 95 percent of the land, were reduced to just 40 percent. By the early 1970s, the underwater grasses that sheltered many species of fish and crabs\u2014grasses that in living memory had been so thick in the river estuaries that boats couldn\u2019t get through them\u2014were all but gone. It \u201castonished the fishermen that the grasses disappeared so quickly and completely,\u201d Brush said. The catches of fish and oysters all dropped.<\/p>\n

Concern was expressed; federal officials took boat trips to see for themselves. Congress created the Chesapeake Bay Program, an unlikely but high-functioning collaboration between 19 federal agencies, 40 agencies in six states and the District of Columbia, 1,800 local governments, 20 academic institutions, and more than 60 nongovernmental organizations. Money\u2014US $27-million\u2014was raised. Blame was laid: overfishing, toxic effluent from industry, sewage\u2014or maybe all these, plus a bust phase in the bay\u2019s normal boom and bust cycle. \u201cI knew about this,\u201d Brush said. \u201cAnd I thought, \u2018Gee whiz, if we could take [sediment] cores we could see what it was like before the fisheries\u2019 decline.\u2019\u201d<\/p>\n