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The Winemaker's Dance is animated by the voices of Napa's winemakers talking about their craft. The book also contains two driving tours through the valley that highlight the landscapes and wineries discussed. An array of unique illustrations—including shaded relief maps overlaid with color aerial photographs—provide a new and illuminating look at the region: its bedrock, sediments, soils, sun, wind, and rain. The expansive narrative considers how these elements influence wines from particular vineyards and how specific winemaking practices can bring out or mask aspects of terroir. It concludes with a discussion of the state of the winemaking industry today.
Unraveling the complex relationship between the people, the earth, and the vines of Napa Valley, The Winemaker's Dance brings the elusive concept of terroir to a broad audience, adding a vibrant dimension to the experience of the valley's wines. It also provides insights that enhance our understanding of wines and winegrowing regions the world over.
1. Birth of a Valley
2. The Underpinnings of Terroir
THE TOURS: PART ONE
3. Great Wine Begins with Dirt
4. The Land and Its Climate
5. Civilizing the Vine
THE TOURS: PART TWO
6. The Winery: Preserving Character or Shaping Style?
7. The Winemaker’s Dance
8. Some Final, and Fundamental, Issues
FLYING FROM DENVER to San Francisco at thirty-five thousand feet, you see below, west of the Rocky Mountains, a vast desert cut through by sublinear mountain ranges. This geologic province, known as the Great Basin, extends from the Utah-Colorado border west for several hundred miles. Seared brown flats, with the remains of lakes long ago dried up, separate mountain heights and discourage most human activity. Anonymous dirt roads that seem to come from nowhere end in small clusters of buildings. It is a land that breeds paranoid fantasies of men in black uniforms, of UFOs crashing and being hidden by the government, a land some think inhabited by space aliens.
Patterns on the ground, abstractions in a brown-on-brown palette, record the water flow from snowmelt and rare rainstorms. Mesmerized by mile on mile of this scrolling canvas, you might be jolted by the sudden appearance of steep forest-clad slopes. They rise abruptly, cut by deep canyons, topped by bald gray knobs that roll away north and south into the distance. In the low sun of early morning or late afternoon, curving knife-edge ridges stand out, linking one sharp peak with another. These are the walls of glacial cirques,high-altitude bowls carved when the mountains were host to year-round ice and extensive alpine glaciers. These mountains, the Sierra Nevada, are the cause of the desert that fills the land to the east. Moisture-laden air rises up the gentle western face of the mountains, cooling as it goes, dropping most of its cargo of water on the heights and leaving little for the other side. The desert lies in the rain shadow of the Sierra, and a broad shadow it is.
Crossing the Sierra and moving on toward San Francisco, you may note the long western gradient of the mountains, carved by deep canyons that drain snowmelt and rain. These canyons have the U-shaped form that comes from scouring by valley glaciers; one is the canyon of Yosemite, its cliffs known as American icons.
Gradually the forests give way to scrub growth, and the gentle slope of the mountains merges with the floor of the Central Valley. This great trough runs the length of central California, from Bakersfield in the south to Red Bluff in the north, drained by the San Joaquin River in its southern part, the Sacramento in the north. The valley floor is a quilt of farms, one of the most productive agricultural regions in the world. If not for water from Sierra snows, stored for summer irrigation, this too would be a desert, caught in the rain shadow of the Coast Ranges.
Those hills, farther west and rising to more than four thousand feet, form the western boundary of the Central Valley and the western margin of the continent. The relatively affordable suburbs of the Bay Area swarm along the eastern flanks of these hills, while the cities and more upscale suburbs hug the shores of San Francisco Bay.
If you're flying into Oakland or taking a northern approach to the San Francisco airport, you might notice a couple of valleys that begin at the northern tip of San Francisco Bay. The smaller one to the west is Sonoma; the other is the Napa Valley. Depending on visibility, you might even be able to discern Napa's two parts, a wider southern portion and a narrow northern extension. The valley is the result of a long and complex series of events that tell the tale of how the western margin of North America was formed, a land that was not here 145 million years ago. The story of terroir in Napa begins that far back, when the foundations of the valley began to take shape.
SHAPING THE FOUNDATION
If you had flown over the Sierra 145 million years ago, the picture spread beneath you would have been vastly different, looking more like the Aleutian coast of Alaska, where flight patterns are often interrupted by volcanic activity. Your plane might have had to dodge thick plumes of ash, for the Sierra Nevada of that time consisted of a string of volcanoes that extended the length of the current range. These volcanoes formed from magma that rose as the Farallon plate descended beneath North America. Today's Cascades are the northern and most recent extension of this ancient Sierran volcanism.
The coast was only a few miles to the west of the volcanic range, perhaps like the Peruvian or Chilean coast of today, where the mountains rise steeply out of the Pacific Ocean, climbing to twenty thousand feet within thirty miles of the shore. Scaling a Sierran peak of that day would have been a more difficult and dangerous task, but the view would have been impressive. You would have seen a group of volcanic islands much like the Philippines or Indonesia some distance offshore. These islands, borne on the Farallon tectonic plate, were inexorably approaching the coast. Within the next 5 million years, they would slam into North America and slide below its surface, crushed between the two plates and smeared onto the continent, beginning the creation of all of California west of the Sierra Nevada.
During subduction, in which plates or continental masses meet, one slides beneath the other, descending into the mantle, the distinct layer immediately below the Earth's relatively thin crust. On continents, the crust averages about forty miles in thickness; on the ocean basins, about ten (Figure 1). While this difference sounds large, on the scale of Earth it becomes imperceptible, like the variations in thickness in the skin of an inflated birthday balloon. The mantle that lies below the crust is rock under intense pressure and at progressively higher temperatures toward the core, the metallic center of the planet (see Figure 3). Composed of nickel and iron, the outer layer of the core is solid, while its innermost portion is a liquid nearly as hot as the surface of the sun.
As the lower plate slides down into the mantle, friction between the plates heats the rock, while entrained water lowers its melting point. At a depth of about sixty miles, the rock begins to melt. The molten magma rises through the mantle as small blobs and strings, driven by differences in temperature and density. This material rises until its density, lowered by cooling, matches that of the surrounding rock. There it accumulates, forming magma chambers some thousands of feet beneath the surface. Eventually the surface above begins to wheeze and crack under the pressure of the rising magma, which erupts either with an explosive roar, as Mount St. Helens did, or more gently, with lava flowing onto the ground in the style of Hawaiian volcanoes such as Mauna Loa. The difference lies in the composition of the fluid-with more silica, the major component of Earth's crust, the magma becomes more viscous and less likely to flow, with a greater tendency to explode suddenly.
The volcanic islands that slid beneath western North America so many millions of years ago are preserved in ocean crust rocks that lie within the foothills of the Sierra. No longer readily identifiable as islands, they exist today as isolated fragments that have been smeared out against the edge of the continent. Imagine the Philippine Islands approaching the Chinese mainland, closing the South China Sea, and then slowly sliding beneath the coast of China, crushed between the Pacific and Eurasian plates, and you'll have a picture of what was happening in California.
Given the scale of this event-an island mass colliding with a continent-the effects were far-reaching. The molding of the volcanic arc into the underpinnings of North America, a bit like squashing a piece of red clay onto the edge of a slab of green, changed the character of plate movement. The position of plates on the globe had remained unusually stable for about 80 million years, during the period that stretched from 140 million years ago to about 60 million years ago. But at the beginning of this period, some 5 million years after the islands disappeared beneath North America, the subduction zone that marked the western boundary of North America suddenly and mysteriously jumped far to the west, trapping a chunk of ocean crust and adding it to the North American plate. This chunk, now known as the Coast Range ophiolite, forms the foundation for all the other materials that later came together to form the land we call California.
We might say, in summary, that the real history of California began about 140 million years ago. At that time, the physical, geologic, and natural western boundary of North America lay some distance west of the actual coastline, beneath the waters of the Pacific Ocean. At this continental edge, the Farallon plate slid beneath North America, creating a range of volcanoes along the coast that were the precursors of today's Sierra Nevada. About this same time, a set of volcanic islands on the Farallon plate was sliding beneath North America.
As the early Sierran volcanoes built up layer after layer of lava and ash, they slowly took on the volcanic shapes we know so well-the perfection of a Mount Fuji, for example, or the magnificence of a Mount Rainier. Gradually, their weight began to depress the crust, creating a deep trough that extended the length of the range. West of the trough, on the edge of the North American plate, a bulge developed in the sea floor. This upwarp in the crust was linked to the formation of the trough-as one part of the crust is depressed, the adjacent one warps up. You can illustrate this by pressing the edge of your hand into a folded towel, forming a trough; the towel will rise on each side, forming a double bulge. (This process is far more important than it might seem from this brief description. Crustal bulges, which are associated with zones of mountain building throughout the world, contain a considerable portion of the oil and gas that have been trapped within the crust.)
You may wonder at the notion of Earth's crust bowing down under an added weight-after all, rocks are hard and unyielding, and we perceive the crust as rigid and fixed. In reality, however, the crust is quite flexible, and it floats, more or less, on the denser mantle below. Think of a steel reinforcing rod used to strengthen concrete. In short segments, the rod is rigid, impossible to bend. But in lengths of twenty feet and more, it bends under its own weight. Rocks are similar: in larger masses, they become malleable. Traveling through mountainous country-the Alps of Europe or the Appalachians and Rockies of North America, for example-you may notice layers of rock that are bent and broken, often in fantastic shapes (Figure 2). These forms reflect the immense forces that accompany the process of continents colliding, which creates pressures and temperatures that cause rocks to flow while changing their mineral composition. As the rocks cool and the pressure is eased, they become rigid and brittle. Although in Napa you won't see folded rocks quite like those shown in Figure 2, you can find rocks tilted up on edge-layers once horizontal that are now sitting vertically-along the Silverado Trail. Similar rock geometries, though not as steep, occur throughout the Vaca and Mayacamas Mountains.
THE GREAT VALLEY SEQUENCE AND THE FRANCISCAN FORMATION
Beginning 140 million years ago, then, and continuing for 80 million years, volcanic ash and lava erupted from the Sierra Nevada volcanoes. Red-hot ash and rock roared down their sides in pyroclastic flows at velocities up to two hundred miles per hour. Massive thunderstorms flooded the mountains, saturating the soft ash and rock that accumulated on their flanks and forming volcanic mudflows (lahars). We have seen these processes in relatively recent years, particularly at Mount St. Helens in 1980, when pyroclastic flows tumbled down the mountainside and lahars clogged the local rivers with mud and forest debris.
During these volcanic eons in the Sierra, rain and snow fell, rivers ran, the seasons followed one another much as they do today. Beset by weathering processes, solid rocks slowly rotted into smaller particles, which were eroded by water and carried into streams. The streams moved them from the mountains to the shore, storing the sediment temporarily in beaches, marshes, and offshore bars. As material piled up near the shore, periodic events-large storms, earthquakes, tidal waves-shook some of the accumulation loose and transported it in giant undersea mudflows into the deep axis of the trough. Here, layers of sand and silt slowly accumulated, each layer representing one of these catastrophic events.
The slurries that deposited these layers are known as turbidity currents. Scientists understand them well in part because they still occur in the deep sea. Turbidity currents were first discovered some decades ago when a series of undersea cables broke in an unusual nonrandom pattern, starting near the coast and progressing farther out to sea. Investigators determined that the cables had been cut in sequence by a strong undersea current carrying a heavy load of sediment. Geologists have now identified the remains of such currents throughout the long history of Earth and in many places, including the Napa Valley.
Volcanic edifices, composed as they are of layers of soft ash, the rubble of lava flows, and other loose debris, do not last long at Earth's surface, at least in comparison to other geologic features-one hundred thousand years is ancient for a volcano. As volcanic activity died out in the Sierra, the volcanoes were worn away by weathering and erosion that exposed their roots, the huge granite masses called batholiths that, when molten, had fed the volcanic activity. The most photogenic of these masses are the fabled faces of El Capitan and Half Dome in Yosemite National Park. Beneath these bodies, ancient ocean crust and pre-Sierran volcanic rocks lay at the foot of the mountains. These, too, contributed material to the sediments that accumulated in the adjacent basin.
For 80 million years, the boulders, gravel, sand, and clay derived from the Sierra and delivered to the trough at the foot of the mountains piled up to a thickness of about fifty thousand feet. Mind you, this is the present thickness of the pile-the depth of water in the basin itself was never more than perhaps a few thousand feet. As the weight of sediment increased, the crust slowly subsided, making space for additional geologic debris. Now solid rock, this accumulation of sandstone and shale is known as the Great Valley sequence. Slices of it, torn from the parent accumulation by the forces of tectonic faulting, form one of the primary bedrock components of the Napa Valley.
The sandstones of the Great Valley sequence are mostly arkose, a rock made up of light-colored, silica-based minerals with a high content of potassium, sodium, and calcium. The rocks are mainly shades of brown and tan, reflecting their mineral makeup.
Excerpted from THE WINEMAKER'S DANCE by JONATHAN SWINCHATT DAVID G. HOWELL Copyright © 2004 by Regents of the University of California. Excerpted by permission.
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