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Ralph S. (Ralph Stockman) Tarr.

A laboratory manual for physical and commercial geography online

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bedded sediments, have been studied to bring out the variation in their topography and devel-
opment as dependent on their age, their elevation, and their location in a humid or arid climate.
The erosion cycle in each of the regions thus far studied may be considered as having con-
tinued uninterruptedly. However, it may happen that what can be termed an unexpected
factor is introduced at some stage in this cycle ; and, in that case, the drainage of the region
is said to have suffered an accident. Such an accident was the occurrence of the period of
continental glaciation in northern United States.

In regions where the topography was irregular and well defined, as, for example, in moun-
tainous or dissected plateau regions, the effect of the glaciation was not of a dominating char-
acter on the appearance of the region as we know it to-day. On regions like the Central
Plains area, on the other hand, which had advanced to the gentle relief of an old-age stage, the
effect of the glacial advance was very marked and striking. (Text-book, pp. 148-149 and
154-156.)

The line of dashes and circles on the diagram map (Fig. 21) marks the outline of the
greatest extension of the ice sheet of the Wisconsin advance of the continental glacier. Plot
this outline in ink on your contour map of the United States, using the same symbols. Fill
in also a legend square, as indicated on the diagram map (Fig. 21).

Where did the continental glacier advance farthest south?



What effect did the presence of

the Appalachian Plateau have on the advance of the ice in the eastern part of the United

States?

Why did the region around the western end of Lake Superior have a similar effect?

What comparison can you make regarding the number of lakes within and outside the area
of glaciation ?

149



What suggestion as to the origin of the basin of Lake Michigan do you find on

comparing the direction of its extension and that of the ice lobe that covered this region ?



To which of the other Great Lakes might this explanation be also applied ?



Is the region of

densest population of the United States within or outside of the area of continental glaciation ?



Study of a The Whitewater (Wis.) sheet illustrates conditions which are more or less common in

section of ^ a ^ p ar ^ f ^ e Central Plains within the area of continental glaciation. Locate the position

Plains ela- °^ *^ e sheet on your United States map, and outline its area with ink. Letter or write in the

ciated area. name of the sheet -

Is there any system to the topographic features shown on this sheet ?

What is the condition of the drainage of the area ?



Have the streams any general direction of flow? How can these drainage

conditions be accounted for by assuming the former presence of a great ice sheet ?



What would be the effect, on a region in an old-age stage of development, of dumping great
masses of debris without regard to order or system in arrangement, or amount deposited, in

any one place? :



150



Why is the drainage system in a glaciated area said to have suffered an accident?



What is the origin of the many lakes ?



The band of low hills and depressions which extends across the southeastern portion of
the sheet is a terminal moraine. Make a cross section of it on a line between the northern
end of Lauderdale Lake and the word " Prairie " of the Prairie du Chien division of the Chi-
cago, Milwaukee, and St. Paul Railroad. Let one section of the cross-section paper equal
twenty feet in the vertical scale.

Describe the topography of a moraine ridgeUs shown by this cross section.



What is the cause of the small lakes and ponds on the moraine ridge ?



Human What pattern of roads was attempted in this area ?

occupation.

What features interfered with carrying it out?



What reasons seem to justify the building of wagon roads across the large swamps ?







How are the courses of the roads affected in crossing the moraine ridge ?



How could large areas of this region be reclaimed for agricultural purposes ?



151



XXXV. —A REGION OF DRUMLINS

Materials. For Each Student. — The contour map of the United States. The Weedsport (N.Y.) sheet.

Purpose. To study a striking topographic phenomenon due to continental glaciation.

Introduc- Over several large areas within the region of continental glaciation in the United States

tor y- {e.g. in Massachusetts, New York, and Wisconsin), the ice sheet produced remarkable clusters

of low hills, to which the name drumlin has been given. Their height, shape, and alignment

afford evidence as to the direction and nature of the ice movement. So far as known the

drnmlins are, in the main, composed of unstratified clay and bowlders, called till. (Text-book,

pp. 152-153.)

Study of a The Weedsport (N.Y.) sheet shows a typical drumlin area. Locate this area on your

drumlin United States map, and outline it with ink. Letter or write in the name of the sheet beside

area. ^he rectangle.

What is the most striking topographic feature of this sheet?

What is the pattern, or arrangement, of the many hills ?

What is their general compass direction?

What would you infer from the arrangement and development of the drumlin hills as to the

direction of movement of the ice mass which made them ?

How do the drumlins influence courses of streams ?

Study of Are the lakes and swamps in this area due to the presence of the drumlins ?

• individual
drumlins. Draw, freehand, small longitudinal profiles and width cross sections of a number of

drumlins in the space provided on the next page.

153



On which end have they the steepest slopes? What variation is there

in the slope and shape of the other end?



Does the slope of the two sides also vary in any one typical drumlin ?

What is the height (from base to top) of six different drumlins on different parts of the

sheet ?



What is their average height ? What is their average width ?

How do they vary in length?



Human Why would tillage be difficult on all parts of drumlins ?

occupation.



What conditions interfere with agricultural pursuits in many of the depressions between the

drumlins? How have the drumlins affected

the courses of the wagon roads and railroads?



154



Materials.
Purpose.

Introduc-
tory.



General
features of
the Niagara
River.



Upper
Niagara.



Lower
Niagara
River and
the Niagara
Escarp-
ment.







XXXVI. — THE NIAGARA REGION

For Each Student. — The Niagara Falls and vicinity sheet, published 1901.

To study the course and physiographic relations of the Niagara River.

The Niagara River is a stream which owes its existence to the effects of the continental
glacier. Before the glacial period the drainage of this region was of an altogether different
nature, and there was then no important stream having the course of the present Niagara.
Therefore the Niagara River may be studied as a young river whose course is due to the acci-
dent of glaciation. (Text-book, pp. 330-334.)

What is the source of the Niagara River ?

Where is its outlet? What is its approximate

length? What is its average width (considering both arms) above

the Falls? Below the Falls ?

In which part must it be deeper and more rapid ? _.

What is the topography of the region over which the upper Niagara flows ?

Make a cross section on a line between Inland and Pull-
man (near Buffalo). Let one section of the cross-section paper equal forty feet in the vertical

scale. What is the nature of the banks of the upper Niagara River?

How does this cross section compare with that of the Mississippi?

Why is the upper Niagara River free from sediment ?

Why is it free from floods?

'. What is the elevation (approximate) of the upper

Niagara Plain (Erie Plain)?

What is the elevation of the Lower Niagara River Plain (Ontario Plain) near Lewiston?

By w r hat topographic feature are the two plains separated ?

How

high is the Niagara Escarpment ? How steep is its , slope near the

Niagara River?

155



In what direction does the escarpment extend ?



Make a cross section across the lower Niagara River on a line between

Four Mile Creek and the Michigan Central Railroad. Use the same vertical scale as in the

cross section of the Upper River. How do the two cross sections compare ?



The gorge How long is the gorge section of the Niagara River ?

section of

theNiagara What marks the limit of its upstream extension ?

River.

What marks the limit of its downstream extension ?

At which end is it growing longer?

What was the first position of the Falls ? (Text-book, p. 332.)

If

the cataract receded at the same rate as at present (about 5 feet per year), during all the

period of its existence, how long did it take to cut the gorge?

Why are hachures, instead of contour lines, used on the gorge section of the



Make a cross section of the gorge (extending two miles on either side) on a line
parallel to the Niagara Escarpment and one mile south of it. Use the same vertical scale as
in the preceding cross section, and assume that the gorge is as deep as the escarpment is high.
Describe this cross section and compare it with those of the upper and lower Niagara River.



Why is the river so much narrower in the gorge than on either plain ?



156



What evidence is

there that the northwest bank of the Whirlpool is made of softer material than other parts of

the gorge wall ?



The Falls. How high are Niagara Falls ? What is the

outline of the crest of the Canadian Falls? _•

The American Falls ? Why has the Niagara

Eiver a greater sediment load below than above the Falls ?

In what way does the presence of Niagara Falls and Gorge affect navigation ?



How does

this account for the location of Buffalo ?



Why is there not a city of equal importance at the

southern end of Lake Huron ?



Where does the Erie Canal begin ? .



What reasons can you
give for the location of Tonawanda ?



157



Why is the shipping of Lake Ontario of less impor-
tance than that of the upper Great Lakes ?



Why are there many manufacturing establishments at Niagara Falls City ?



How will the

further development of Niagara power affect the surrounding region ?

What other reason

can you give for the location of a city at Niagara Falls ?



t



158



XXXVII. — PLAINS CITIES AND THEIR ENVIRONS

Materials. For Each Student. — The Cleveland and Vicinity sheet, the St. Louis sheet, the Denver quadrangle.

Purpose. To gain an appreciation of the factors which influence the location and growth of cities, and

the effect of the cities on, and their response to, their physiographic environment.

Introduc- i Cities on the seacoast, and in mountains, which grow to a large size, owe their growth, in
tor y- the main, to some especially favorable factor of environment which dominates all other dis-

advantages the site may have. In the case of plains cities, however, there is a wider variety
of possible locations, and the large city becomes established because of a variety of interacting
lesser influences combining to give one site an advantage over its rivals. (Text-book, pp. 166,
312, 315, 375-377.)
Broad Examine the topographic sheets for the cities of Cleveland, St. Louis, and Denver. What

relations. jg the one dominating factor which made possible the growth of Cleveland and St. Louis ?



What topographic feature prevented the growth of a large city farther to the west than is

Denver ?

Why are transportation conditions of such supreme importance in fixing the sites of great

cities ?



What are the chief industries of cities ?

Of what advantage is it to a city to have a rich

agricultural country immediately tributary to it?



Cleveland and St. Louis ?



How would this fact affect the growth of Denver as compared to



159



Is Denver of more importance as a commercial center, or as a

manufacturing center?



Note that the growth of Denver has been a radial one, — that is, from the center outwards.
What is the significance of this' in regard to the favorableness for habitation of the surround-



ing area?



Cleveland has grown outwards from the diameter of a circle. What reasons can you assign
for this fact?



Why, on the other hand, has the growth of St. Louis been focused on the circumference of a
circle ?



What are the two great interior waterways of the United States ?



On which of these is

St. Louis located? Cleveland?

What advantage has Cleveland with regard to the location

of the eastern coalfields which enables it to compete with Chicago ?



Why can St. Louis

successfully compete with Chicago in marketing her manufactures in the Southern States ?



160



What is the elevation of the land on all sides of Denver as compared to the site of the city
itself ? What advantage does such a site offer

m

^^ as compared to the adjacent areas?



Exact Why is St. Louis located on the west, and not on the east side of the river ?

location.



Why have no extensive suburban districts been built on the east side ?



What was the influence of the Cuyahoga Kiver in determining the exact site of the early
Cleveland? , „

Why has the city grown more to the east and west than to the south ?



What advantage does Denver derive from being on the South Platte River ?



What advantage from being near the base of the mountains rather than farther out on the
plains ? !



Environs of What effect has the presence of a city on the direction of the main roads in the surround-

cities.

ing region ?



161



OF THE

UNIVERSITY



Which, St. Louis or Cleveland, is the objective point of the greatest number of railway lines ?

What does this suggest as to the relative

importance of railway transportation to the commerce of these two cities ?



From what directions do most railway lines enter Denver? ^

Why so few from the west?

Why are there generally many short roads, numerous houses, and small towns in the
immediate vicinity of large cities?



What is the nature of the agricultural products raised on farms near large cities ?



What is the significance of the many short, canal-like branches which extend from Clear
Creek and Ealston Creek near Denver?



Write a short paragraph, stating some of the important factors which influence location
and growth of large cities, and the effect of the presence of the cities on the surrounding

country.



162



Materials.



Purpose.



Introduc-
tory.



Location
and extent
of the
Folded Ap-
palachians.



XXXVIII.— THE FOLDED APPALACHIANS

For Each Student. — The contour map of the United States. The Monterey (Va.-W.Va.)
sheet, the Delaware Water Gap (Pa.-N.J.) sheet. Colored pencils.

To study a mountain region ivhose topography is the result of the upfolding of sedimentary
rocks, and their later denudation.

True mountains are either regions where rocks which were once horizontal have later been
folded, faulted, and metamorphosed ; or regions in which the rocks are crystalline in character,
and generally with a very complex structure. These crystalline rocks often constitute a core
underlying mountains made of folded sediments, and are exposed to weathering and denuda-
tion only after the overlying masses have been worn away.

The Appalachian mountains are interesting in that they include both types : (1) moun-
tains composed of folded sediments; and (2) mountains which are made up wholly of crystal-
line rock. Moreover, the most eastern belt of the Appalachians consists of crystalline
mountains which have been worn down until only their roots remain, and their surface resem-
bles a plain in topography.

This exercise is a study of the western belt of the Appalachian Mountains, which are
made up of folded and then denuded sedimentary strata. (Text-book, pp. 101-105.)

Figure 21 shows the province of the Folded Appalachians, marked " Folded Appalachians."
Plot the outlines of the Folded Appalachians on your contour map of the United States.

What parts of what states are included in this province?



What is the general trend of these mountains?

How do you account for the fact that

they do not appear in the Mississippi Valley, but reappear in Arkansas?



Estimate the length

of the whole system. What is its average

width? What proportion of the area of the

United States east of the Mississippi do the Folded Appalachians constitute ?

163



Appalachian Ridges on the Monterey (Va.-W.Va.) Sheet
On a Line from Southeast to Northwest across the Map



No.


Namk of Ridge


Elevation


No.


Name of Eidge


Elevation


1


Mill Mountain


2500 ft.






















































\







































If they are so narrow, and occupy so small a relative area, why is it that they have so much
importance, as compared to plains regions, in the popular mind?



_• What is the average (ap-
proximate) elevation of the Folded Appalachians as shown by the contours on the United

States map ?

With red pencil color in (with parallel ruled lines extending from northeast to south-
west) the province of the Folded Appalachians. Fill in a legend square, as indicated on the
diagram map, and mark it Folded Appalachians.

164



Study of
a typical
area in the
Folded
Appala-
chians.



Locate the Monterey (Va.-W.Va.) sheet on your United States map and outline its area
in ink. Letter in the name of the sheet. What is the most pronounced topographic feature



of the Monterey sheet ?



What is the general trend or direction of the ridges ?



Starting at the southeast corner, and following

a diagonal line to the northwest corner of the map, set down in the table on page 309, and in
order, the names of the ridges you cross and the elevation of their tops.

In which part of the area are the ridges highest ?

Where are they lowest? What is the nature of the

variation in elevation shown by the intervening ridges ?

_. If the valleys were all filled up to

the level of their bounding ridges, what would be the topography and slope of the country ?



W T hat is a peneplain ? (Text-book, p. 102.)



Develop- Just before the last great mountain uplift (in Tertiary time) the province of the Folded Appalachians

ment of was probably a plain, having a general slope from northwest to southeast. Although the surface of the plain

the present was comparatively smooth, the rock structure beneath the surface was made up of great folds of rocks varying

topography very mucli in the degree of their resistance to weathering and denudation.



of the
Folded
Appala-
chians.



Make a cross section along a line between the towns Clover Creek and Mill Gap. Let one section of the
cross-section paper equal 100 feet in the vertical scale. What would be the direction of flow of the principal

streams on a plain sloping as stated above ? Would this

direction of flow be parallel to or across hidden folds? .

Would the valleys of such streams be widened most rapidly where the folds had brought hard rocks near the

surface, or where they had brought up soft rocks ?

Which tributary valleys would be cut most rapidly, those

flowing along the hard surfaces or the soft ? What kind of

rocks (hard or soft) do the present ridges mark ? Why are

the valleys between ridges so wide as compared to the ridges themselves ?

Name several places where the

streams have cut across the ridges. .

Why are their valleys so narrow at these points ?

What is a water gap? (Text-book, p. 103.)

165



Why are the main streams now flowing southwestward, between the ridges, instead of flowing to the south-
east in accordance with the former slope of the plain ?



Human What are the main lines of travel in this region, as indicated by the direction of the roads

occupation.

and the location of the towns ?

Where do roads cross the ridges ?

What reasons can you

suggest for the general absence of railroads ? '.



Examine the Delaware Water Gap sheet.

Where do the railroads cross the Kittatinny Range ?

Why is this water gap more important

as a transportation route than those on the Monterey sheet ? :



■ Examine your United States

contour map. What other large streams have cut across the Folded Appalachians ?

166



Why have these large water gaps been so important in the history and development of the
United States ?



167



Materials.



XXXIX. — THE CRYSTALLINE APPALACHIANS

For Each Student. — The contour map of the United States. The Mt. Mitchell (N. C.-Tenn.)
sheet, the Monterey ( Va.-W. Va. ) sheet. Colored pencils.

Purpose To study the topography and settlement of a mountain region of crystalline rocks in a mature

stage of dissection.



Introduc-
tory.



Location
and extent
of the
province of
the Crystal-
line Appa-
lachians.



The Crystalline Appalachians lie to the east of the Folded Appalachians, and include
the highest peaks of the Appalachian system. They were lofty mountains before the Folded
Appalachians were formed, and had been so long subjected to denudation that they were worn
to a condition of low relief. Then, in the uplift which elevated the region of the folded Ap-
palachians, these crystalline mountains were also reelevated, and it is to this later uplift that
they owe their present height. (Text-book, pp. 298 and 308.)

On your contour map of the United States plot the outline of the province of the Crystalline
Appalachians as shown on the diagram map. What important section of the country is al-
most wholly included within the province of the Crystalline Appalachians ?

What notable irregularities in the width of this province are

apparent? 1



In what sections of the province are the greatest elevations ?

Which section has the lowest

altitudes? How does the amount of elevation

affect the density of settlement as indicated by the cities?



Study of an
area in the

^Crystalline
Appalachi-
ans.



Color in, with red pencil (using crosses as indicated on the legend square of the diagram
map), the province of the Crystalline Appalachians. Fill in the proper legend square and
mark it Crystalline Appalachians.

The Mt. Mitchell, (1ST. C.-Tenn.) sheet is chosen to illustrate the topography of the Crys-
talline Appalachians. Locate the position of this sheet on your contour map of the United
States and outline its area with ink. Letter in the name of the sheet.



169



What pronounced difference in the distribution and character of summit areas is apparent
on comparing the Mt. Mitchell and the Monterey sheets?







What is the highest elevation shown on the Mt. Mitchell sheet?

What is the elevation of the lowest peaks ?

Is there any regularity in the

distribution of peaks of a certain elevation? What reasons can you suggest to

account for this?



How does the size of the streams shown on this sheet compare with those on the Monterey
sheet?



Why should the Mt. Mitchell region be a divide area ?.



Make a cross section along a line (N. W. and S. E.) between Laurel Knob and Big Tom
Wilson's, crossing Mt. Mitchell. Let one section of the cross-section paper equal 100 feet
in the vertical scale. Compare this cross section with the one from the Monterey sheet.

What difference in the width of the valleys and ridges is shown?



170



^^ Human How do the courses of the roads in this region compare with those shown on the Mon-

occupation.

terey sheet? ___.



Why have the roads on the Mt. Mitchell sheet so many short, sharp turns?

How does the

topography influence the course of the railroad?



Why has this region extensive forests?

As indicated by some of the place names on the map,

what kinds of timber grow here ?



What is the most important town on the Mt. Mitchell sheet?

In a general way (as 1000, 2000, etc.) estimate the number of its inhabitants.

Why are there no more important towns in the area?



Suggest a reason why the New England section of the Crystalline Appalachians has more im-
portant towns.



171



Materials.



XL. — THE APPALACHIAN PIEDMONT AREA

For Each Student. — The contour map of the United States. The Farmville (Va.) sheet,
the Mt. Mitchell (N.C.-Tenn.) sheet. Colored pencils.

p To study the topography of a very old mountain region, and its adaptation to settlement

and agriculture.



Introduc-
tory.



Location
and extent
of the
Piedmont
Area.



The rocks underlying the Piedmont Area are crystalline, and are complexly folded and
faulted. They vary greatly in structure and hardness ; but the region has been so long de-
nuded that its summits have all been worn down to a low relief, and its drainage system is


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Online LibraryRalph S. (Ralph Stockman) TarrA laboratory manual for physical and commercial geography → online text (page 8 of 16)