Our sojourn across the U.S., going from east to west, begins at Boston. The Landsat image covers that city, eastern Massachusetts, Cape Cod, and Providence in Rhode Island. The geology of this region is governed by ancient crystalline rocks that form the lower units in the now much-eroded eastern Appalachian mountain system. The entire region has been glaciated.
New England
With this framework for describing and interpreting the various landscapes that make the U.S. so picturesque, we now embark on a simulated flight over the continent, using mainly Landsat images to portray typical surfaces in many of the provinces discussed above. We start on the East Coast in Massachusetts (which is also in a lithologically distinct part of the Appalachians) and proceed westward along a meandering line that brings us into northern California. Two of the images deviate south of that line but were chosen because they are excellent examples of the terrains and land uses in the provinces they represent. We recommend that you keep an Atlas nearby to help in locating the features mentioned in the descriptions that follow. We do not provide exact route maps for the Tutorial. We think this self effort is good practice for learning how to relate space imagery to geographic data sources.)
The first scene from space lies within the New England Maritime physiographic province.
6-3: For this image and, if you wish for all subsequent ones examined during this transcontinental overflight, locate the scene in your atlas. This will reveal to you the name of the largest blue area (typical of a metropolitan area) and will aid in correlating text to geography as mapped. What is the main city involved and where is it? ANSWER
6-4: Locate the town of Plymouth in Massachusetts; what famous event happened there? Is Gloucester in the image; where? ANSWER
6-5: Out in the ocean north of Sandy Hook is a peculiar curved cloud pattern. It is probably not a natural cloud. Speculate on what might have caused it. ANSWER
Geologically, this region is part of the Appalachian Mountain Belt that passes northward through Nova Scotia and Newfoundland. Most of the rocks underlying the province are igneous and metamorphic. We usually associate these rock types with the deeper parts of an orogenic belt, where temperatures and pressures were higher during their formation (this belt is within the Appalachians; see next page). Their presence at the surface today implies extensive erosion that stripped away the overlying sedimentary rock units after the main episode(s) of mountain-building and uplift. The landscapes typical of New England resemble parts of the Canadian Shield. Flatter areas are interspersed with low mountains, although peaks, such as Mt. Washington in New Hampshire and Mt. Katahdin in Maine, reach elevations exceeding 1,890 m (6,200 ft) and 1,590 m (5,200 ft), respectively. The rocky soils in the region do not favor farming, so that much of the land remains in forests. The predominance of deciduous trees accounts for the widespread reds in this false color composite (above). Most of New England experienced one or more advances of the Pleistocene continental glaciers that removed soils, laid down deposits, and carved out lakes.
The most conspicuous feature in this scene is Cape Cod, an east-west landmass built from extensive end morainal deposits that mark the southern boundaries showing how far glacial ice sheets advanced. A closer look by radar shows the many small lakes in the Cape (note the canal shortcut):
The sharp bend that ends at Sandy Hook represents, in part, modifications brought on by ocean-wave action. South of the Cape are the islands of Nantucket and Martha's Vineyard, also originating from fluvioglacial action. All three are noted vacation spots. Lowlands associated with drowned rivers make up Buzzards Bay off the west end of the Cape and Narragansett Bay below Providence, Rhode Island.
The bluish area along the Massachusetts coast is the central part of greater Boston whose harbor lies within Boston Bay. Here is where we start our western flight - from Logan International Airport. As seen by the Landsat-4 TM, that area looks like this:
This map of Greater Boston should help you to get your bearings. Fit the scene above and the scene below in it.
An astronaut photo taken from the International Space Station shows part of inner Boston and sections to its north in some detail. The center of the city is the Boston Common; the large Logan Airport makes this a frequent destination for travelers, including those going to Europe.
Now for a history lesson. Look at this map of Boston in 1775. Compare that with the map above and the ISS image. Before reading on, try to single out the main differences:
There appear to be many changes since the Revolutionary War. At that time, Boston itself was almost an island, with only a narrow stretch of land - the Boston Neck - connecting it to the mainland. Both the Boston Harbor and the Back Bay (Charles River) were much more extensive then. What has happened should be obvious (certainly not sealevel fall, exposing land, since modern sealevel is rising slowly): huge amount of dirt fill have been dumped into the harbors, creating new land and expanding the Neck to its present width. The Charles River has been narrowed (but still wide enough upstream for sailboating). Noodle Island has been added to, enough to allow construction of today's Logan International Airport.
The Revolutionary War began on April 19, 1775 at Lexington and Concord, suburb towns about 35 km west. The first important battle took place on June 17, 1775 at Breeds Hill/Bunker Hill just north of Boston proper (then, a town of about 16000 people). Bunker Hill rose 110 ft from the river. This fight, commanded by British Gen. Wm. Howe, involved several charges by the "Redcoats" under General Thomas Gage that finally drove off the Colonial Minutemen and other militia under General Israel Putnam (although Col. Wm. Prescott was the actual field commander, but many historians credit Putnam with the immortal command "Don't fire until you see the whites of their eyes."). Although technically this was an English victory, their heavy losses - 226 dead (Americans 140 killed) and 828 wounded - shook their confidence in an easy quelling of the Rebellion
Gen. Howe thereafter holed up in Boston, surrounded by Americans to the north and west. His failure to capture the Dorchester Heights proved fatal. In the dead of winter, the Americans led by Henry Knox hauled captured cannon from Fort Ticonderoga in New York (which had been stormed earlier by Ethan Allen and Benedict Arnold) through snowstorms back to Boston - a feat requiring two months. General George Washington, the newly appointed Commander-in-Chief, set the cannon up on Dorchester Heights. The fear of uncontested bombardment eventually forced the British to evacuate Boston (by sea, going first to Nova Scotia, until attacking Long Island and then New York in August) on March 17, 1776 ("Patriots Day"), leaving New England untouched for the rest of the war.
This GoogleEarth image portrays most of present day downtown Boston (area at word "highway.." in the ISS image). Note how some streets curve. This accounts for why the writer (NMS) started west on one of these, thought he was going straight (failed to note the curvature), turned right, ended up at Boston Harbor instead of on the way to MIT (located at word "Charles" in the astronaut photo).
An aerial oblique photo shows this downtown area, the Boston Commons, Back Bay, and the John Hancock building (foreground).
The writer (NMS) would be remiss if I miss the opportunity to show my last Alma Mater, the Massachusetts Institute of Technology (MIT) where I was awarded the Ph.D. in 1958. Here are an aerial view showing the campus on the Cambridge side of the Charles River and again in a 2 meter color space image of the campus center made by the Quickbird satellite.
In recent years to offset the traffic snarls and confusion, tunnels under the Bay and broad limited access highways right through town have improved the traffic flow. This Quickbird image shows a part of this transit system, along with striking new modern tall rises:
Near the bottom left of the first Landsat scene above is another large blue area - the characteristic signature of a metropolitan region. Its location on Naragansett Bay gives its identity away - it is Providence, capital of Rhode Island, the U.S.'s smallest state. Here is a picture of its downtown buildings:
North and east of Boston is the home of the "Down Unders" - the citizens of Maine. Here is coastal and inland Maine in winter:
The igneous-metamorphic rocks underlying much of Maine were extensively glaciated in the Pleistocene. Brown areas - set off by snow - are low hills which are covered by fir trees and some birch and maple trees. The indentations caused by the glaciation are partly responsible for the rugged irregular coastline that is being inundated by post-glacial sealevel rise. The last landmass on the right of the image that projects into the sea is Mount Desert, on which Bar Harbor is situated. Lewiston, Brunswick, Augusta, Waterford, and Bangor are in this scene (since your atlas should be open, find them).
Southern New England is also made up of crystalline rocks that are an extension of the Piedmont to the southwest. The Landsat scene below shows early leafing of trees in Connecticut. The Hudson River is on the west; the smaller Connecticut River to the east. New Haven (home of Yale University) is the blue patch along the upper reach of this latter river. The terrain in Connecticut is mostly low rolling hills, cut into crystalline bedrock (its fracturing is faintly evident).
At this early stage in our trip, we will set a precedent that will recur on most of the other pages covering the areas visited in the cross-country journey above the U.S. We will depart significantly from the main geographic region featured on each page to look at other regions often considerable distances away. In this first case, we will examine just one segment of the very extensive Atlantic-Gulf Coastal Plains Province that begins in New Jersey (to its north, this unit is now almost entirely under the sea as part of the Atlantic Shelf) and continues along the Atlantic Seaboard (Florida is usually considered a special landmass included in Plains but with a different geological history) and then wraps around the coastline of the Gulf of Mexico south to the Tex-Mex border (and beyond).
Our single example is in South Carolina, in the part from the Atlantic inward to the Piedmont. This late Fall image taken by Landsat covers the Atlantic Coastal Plain, much of which is now farmlands. Coastal pines dominate the dark areas near the coast. The Santee River has been dammed at Lake Marion, which drains into Lake Moultrie.
At the end of the drowned river valley coming off L. Moultrie is the famed city of Charleston, rich in ante-bellum homes. This city, along with Savannah, GA and New Orleans, LA has well-preserved sections that are a hallmark of the Deep South. Charleston was much involved in both the Revolutionary and Civil Wars. The main city is a "Peninsula" formed at the confluence of the Ashley and Cooper Rivers. Here is a close-up made from Landsat-7 imagery.
A general aerial view of Charleston appears next. Along the eastern waterfront are some of the old homes of Charleston. These home postdate those burned in the Revolutionary War, when Sir Henry Clinton captured the city at the start of the final (southern) phase of battle that ended with Yankee victory at Yorktown.
Across from these homes, about a mile east is Fort Sumter, site of the opening bombardment that touched off the Civil War ("War between the States"). Union troops in the marshes southeast of Charleston laid siege to the city, usually involving artillery attacks. The writer's (NMS) great-great grandfather was a civilian involved in directing an incendiary attack (he invented "Short's Fire") using the famous 'Swamp Angel' cannon. On the 32nd volley, the cannon was damaged enough to stop this attempt to burn down the city.
We will see several other space images of the Coastal Plains (for example, New Orleans, LA) elsewhere in the Tutorial.
Primary Author: Nicholas M. Short, Sr.
