Pillow lava fight helped America win its independence


The July Fourth holiday is both a great time to spend with friends and family and also a time to reflect on our nation’s origins.

The United States gained its full independence through a war that lasted eight years, killing more than 50,000 soldiers because of fighting and disease. It was a tough, bloody campaign, with the Americans struggling in the first years of the war. Things started to turn around for independence-minded colonists, however, with the Battle of Saratoga in upstate New York in 1777. The Americans had a special advantage over the British in that battle: pillow lava.

The Revolutionary War was two years old in 1777, with mixed results for both British and American forces and no clear outcome in sight. The British hatched a plan to end the war by splitting the rebellious colonies down the middle, sending Gen. John Burgoyne’s army from Canada south through the Champlain Valley (along the eastern border of New York), to connect with British troops moving north from New York City.

Burgoyne’s army fought its way down through New York but encountered stronger American resistance near the village of Saratoga in September. The Battle of Saratoga actually consisted of two battles fought over a month, with the American army eventually gaining the advantage and pushing Burgoyne’s army back toward the north. But Burgoyne’s army was still fit to fight another day, and the American army needed to capture it for a decisive victory. That’s where the pillow lava comes in.

American Gen. John Stark, stationed north of the retreating British, worked to cut off their retreat. He hastily positioned his men beside (and probably atop) a steep hill of unusual rock next to the Hudson River. The hill provided both an ideal lookout and, importantly, a bottleneck with the Hudson River that could be used to ensnare the retreating British. The Americans laid in wait, ready to spring the trap.

Stark’s soldiers might have noticed that the rock they were on was unusual, but not that they were on an ancient formation of pillow lava. The lava was erupted more than 400 million years ago, as part of the first stages of plate collision that formed the Appalachian Mountains. At that time, plate tectonic motion was pushing an island arc, similar in shape to Japan, into the east coast of North America. Buckling and tearing of the crust triggered volcanic activity beneath the shallow ocean near the coast, oozing out lava onto the sea floor. Lava erupted underwater tends to form distinct lobes, or “pillows,” and the resulting formations are called pillow basalts. Eventually the lava cooled, and continued uplift during this collision pushed the lava out of the water.

You may have seen video of pillow lava forming, resembling thick, spiny black toothpaste oozing out from incandescent underwater cracks. With Kilauea currently sending lava into the ocean near Kupapau Point, pillow lava is probably forming southwest of Kalapana at this very moment.

As the American army was encircling the retreating British, the last avenue of escape for the British was through the gap between the hill of pillow lava and the Hudson River. With Stark occupying this narrow pass, he essentially “locked the back door,” and the British army was surrounded. The plan had worked perfectly.

Burgoyne surrendered on Oct. 17, and the Battle of Saratoga was won decisively by the Americans. The victory not only provided a morale boost and ended the British plan to split the colonies, it also demonstrated that the American colonists had the potential to defeat the British. Further, this event persuaded France to openly support the American independence cause. The battle is often considered the turning point of the American Revolution, and the humble hill of pillow lava that helped make it all happen is now known as Stark’s Knob.

Who could have guessed that lava oozing onto the sea floor almost a half billion years earlier could have such an impact on the formation of our country? As you celebrate this July Fourth, think about how American independence was facilitated by a hill of pillow lava.

Kilauea activity update

A lava lake within the Halemaumau Overlook vent produced nighttime glow that was visible from the Jaggar Museum overlook and via HVO’s Webcam during the past week. The lava lake level during the past week started off at roughly 130 to 150 feet below the floor of Halemaumau, but then began dropping slightly with minor summit deflation on June 24.

On Kilauea’s east rift zone, breakouts from the Peace Day tube remain active at the base of the pali and on the coastal plain. Small ocean entries are active on both sides of the Hawaii Volcanoes National Park boundary. The Kahaualea 2 flow, fed from a spatter cone on the northeast edge of the Puu Oo crater, continues to advance slowly along the edge of the forest north of Puu Oo.

There was one earthquake reported felt in the past week across the Hawaiian Islands. On June 21, at 12:04 a.m., a magnitude-4.5 earthquake occurred 34 miles north-northeast of Maunaloa, Molokai, at a depth of 21 miles.

Visit the HVO Web site (hvo.wr.usgs.gov) for Volcano Awareness Month details and Kilauea, Mauna Loa, and Hualalai activity updates, recent volcano photos, recent earthquakes, and more; call 967-8862 for a Kilauea summary; or email questions to askHVO@usgs.gov.

Volcano Watch is a weekly article and activity update written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.