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Ralph S. (Ralph Stockman) Tarr.

A laboratory manual for physical and commercial geography online

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Which is the shortest course, around the bends or across the necks of land between them ?

Why does the river often change its course, especially during a

flood when part of the waters can flow over such necks of land?



What does the abandoned portion of the river become after a new course is established?

Give an example of such a change as shown

on the chart.



Why must the river be often resurveyed'



Study of a The Donaldsonville (La.) sheet shows, in detail, typical conditions of this region. Locate

typical Mis- and plot the area of this sheet on your United States map, outlining it with ink. Letter or

sissippi wr ite in the name of the sheet.

Flood-plain

and Delta

area W T hat is the contour interval on this sheet ? Why was not a

larger interval used?

Make a cross section between Bayou Verrette and the nearest point of the swamp on the
opposite (east) side of the river. Allow one vertical division of your cross-section paper for
every ten feet of elevation. On the cross section, indicate the line along which it is made, and
also the horizontal and vertical scale.

126



As shown by your cross section, where are the highest points in the flood plain ?
How do you explain this condition? (Natural levee, Text-book, p. 62.)



In what direction do the small streams near the Mississippi flow?

Why can not the large

swamps be drained?



Why does the Mississippi so readily change its course in flood times ?



What is the stage of the development of drainage conditions here, as compared to those in
the Glacial-Lake Plains regions?



Is this, then, a younger or older region in development than the Glacial-Lake Plains areas ?



Human Describe the position and course of the main roads of this area,

occupation.



How do you account for their arrangement ?



127



What is the direction of the secondary roads ?



.Where do they end ?



What is the average width of the habitable area of the inner flood plain, as shown on this

sheet?

Where are the majority of the houses located?

About how many houses are there along a

mile of river bank? What population per

square mile does this indicate?

Does such a population indicate that the flood plain is rich or poor agricultural land ?

Why is a region with such large areas of swamp land not healthful?



Write a short paragraph summarizing the conditions along the Mississippi River in its
lower course.



128



XXX.— THE COASTAL PLAIN

Materials. For Each Student. — The contour map of the United States. Winterville (N.C.) sheet. Colored

pencils.

For General Class Use. — Fargo (N.D.) sheet. Donaldsonville (La.) sheet.

Purpose. To study a young plain recently uplifted above sea level, and to compare the conditions on it

with that of other young plains previously studied.



Introduc-
tory.



Extent of
the Coastal
Plain.



The region of the United States bordering the eastern and southern coast, from New
York City southward to Mexico, except where broken by the Mississippi flood plain and
delta, is a Coastal Plain. That is, it consists of layers of sediment deposited on the ocean
floor and then, by a change in the level of the land, lifted out of the water. (Text-book, pp.
72-75, 305-306.)

On your contour map of the United States plot the outlines of the areas marked Coastal
Plain in Fig. 21. Estimate what proportion of the area of the United States the Coastal Plain

region constitutes. Of what states does it

form the larger part?



Broad Southern Florida is different from the rest of the Coastal Plain in that it is underlain by

relations. limestone. How may this fact account for the many lakes mapped on its surface ? (Text-



book, p. 60.)



What other region having many lakes have you studied?

What does the presence of lakes and swamps indicate as to drainage conditions ?



Along the inland margin of the Coastal Plain, on the Atlantic coast, the soft, loose sedi-
ments of the plain rest against more resistant crystalline rocks, such as granites, schists, and
gneisses. The rivers of this region flow down across these hard rocks, and then on to the soft
strata of the Coastal Plain. In which of these classes of rock can streams erode the more

rapidly? Why would the •" Fall Line"

(as this contact line of the hard and soft rocks is called) be an especially favorable site for

129



the growth of cities ?.



Make a list of the important cities located along the "Fall Line," and the river on which they
are situated.



On your contour map of the United States color in lightly, with yellow pencil, the area of

the Coastal Plain regions. Fill in a legend square (with yellow pencil also) as indicated on

the diagram map (Fig. 21) and mark it Coastal Plains.

Study of a The Winterville (N.C.) sheet presents, in detail, typical conditions of the Coastal Plain

typical sec- area. Locate and plot the area of this sheet on your United States map, outlining it with ink.

tion of the Letter or write in the name of the sheet.

C 03. S tell

plain What would be the surface topography of a coastal plain just after it was lifted above the
sea?



What has happened to this part of the plain since its uplift above the sea ?



What areas have

conditions resembling the original surface?

What do such divides between streams indicate

as to the age of the region where they occur ?

[ What is the contour interval of this sheet ?

What is the present average elevation of the region above the sea

level ?

130



Profile of a Make a longitudinal profile (in the manner directed in exercise No. XXV) of the valley

Coastal f Hardee Creek from its mouth at the Tar River to its source. Where is the slope of the
^Plain

^^^ ' valley greatest, near its mouth or its source?

What does this indicate as to the kind and position of the erosion which the stream is

accomplishing?



How deep is this valley at a point about two miles from its mouth?

How wide?

What form of cross section has it?

i_ How will this cross section be modified as time passes ?



Comparison What similarities in valley form have the streams on this sheet with those of the Fargo
with drain-
age condi- sheet ?
tions on
other young
plains.



What differences in the conditions in the valley bottoms ?



How may the greater elevation

of the Fargo region help to account for the less swampy conditions on it ?

What is the

elevation above sea level of the major portion of the area of Donaldsonville, Louisiana sheet ?

How does the amount of swamp land there

compare with that on the Winterville sheet ?

What similarity in the nature of the divides exists between the Fargo region and the Winter-
ville Coastal Plain region?



131



Human What is the pattern of the roads on the Winterville sheet as compared to the Fargo sheet ?

occupation.

Is this difference wholly or partly due to a difference in topography ?
What areas do the roads on the Winterville sheet especially avoid ?

On comparing the

courses of the railroad lines and the wagon roads on the Winterville sheet, what reasons can
you suggest for the greater irregularity of the wagon roads?



How does the density of population in this area compare with that indicated on the Fargo
sheet and the Donaldsonville sheet?

How do you account for the difference ?



What do

such place names as " Green's Mill Run," " Harris Mill Run," " Plank Road," " Gum Swamp,"
and the comparative sparseness of the population suggest as to the industry of the region ?



Write a short paragraph summarizing the topographic conditions which characterize the
Coastal Plains province and the nature of its settlement.



132



XXXI. — THE GREAT PLAINS



Materials. For Each Student. — Contour map of the United States. Mt. Carrizo (Col.) sheet, Syracuse

(Kan.) sheet, Kearney (Neb.) sheet. Colored pencils.

Purpose. To study the development of topography, and its influence on settlement, in a region of high

plains which has an arid climate.



Introduc-
tory.



Location
and extent
of the Great
Plains.



The plains studied in the preceding exercises were of comparatively low elevation, and in
a humid climate. The Great Plains region has, in general, a much greater elevation and a
much more arid climate. The rocks, however, are similar in origin and position to those of
the Coastal Plains, — that is, they are sediments laid down in former seas, and still lie in
nearly horizontal position ; but, being more firmly consolidated, they are more resistant to
denudation than the rocks of the Coastal Plains. Therefore, in the Great Plains we study the
topography resulting when a region of plains has been subjected to a marked uplift, and
exposed to the agents of weathering and erosion in an arid climate; also, the effects of such a
climate on the human occupation of the region. (Text-book, pp. 77, 326-327.)

On your contour map of the United States outline the area of the Great Plains, as shown
on the diagram map (Fig. 21). What meridian marks the general eastern limit of the Great

Plains? What determines their western



boundary? What is their approximate ele-
vation above the sea, as shown by the contour lines on the United States contour map ?

How does this compare with the elevation of



the Coastal Plains ?



Parts of what states are included in the area of the Great Plains ?







How do the Great Plains compare in extent with the regions previously studied ?



What is

the general industrial and agricultural development of the Great Plains, as indicated by the
number of important cities on them, and as compared in this respect wifh the regions previ-
ously studied?



133



Color in lightly (with brown pencil) the area of the Great Plains as you have outlined it

on your United States contour map. Also color in a legend square with brown, and mark it

Great Plains.

Study of Locate the position of the Mt. Carrizo (Col.) sheet on the United States map and outline

typical with ink the area it includes. Also letter or write in the name of the sheet on the map.

areas of the

Great Near which border of the Great Plains is this area located ?

Plains.

What is the elevation of this border as compared to the Mississippi

Valley in the same latitude ?

What average slope (approximately) would this give to

streams flowing toward the east ?

How would such a slope affect their power of erosion?



Topog- Make a cross section along a line extending from a point 2 inches southeast of the last

raphy of « a " in Animas, through the " z " in Mt. Carrizo, and continuing for 3£ inches in the same
the western diction. Use the same horizontal scale as that of the map, and let one division of the cross-
section paper equal one hundred feet in the vertical scale.

What is the nature of the stream valleys as shown by this cross section ?



What does the fact that the streams are marked by dotted blue lines indicate ? (See Fig. 20.)
If after a long dry period, a heavy rain occurred, why would the water drain off quickly ?

What would be the effect of this rapid run-off on

the stream valleys?

Why would erosion be more effective than weathering in this region? .

134



What is the topogra-
phy of the divide areas between streams ?

Describe the shape, slopes, and top of Mount Carrizo as shown by the map and your cross
section.



Is it a true mountain ? What kind of a land form is it ?

Why do mesas develop extensively in arid and not in humid regions,

even though both have horizontal strata?



What is the difference between a butte and a mesa

as illustrated in Potato Butte and Fowler Mesa?



Human Some habitations are undoubtedly located in this area, but they are not shown on this

occupation map. What, however, does the small number of roads indicate as to the extent of settlement ?
along west-

What two conditions would prohibit dense set-
tlement in this region ?



Topog- Locate the position of the Syracuse (Kan.) sheet on the United States map and outline

raphy of with ink the area it includes. Also letter or write in the name of the sheet on the map.

the Central What reasons can you suggest why the southern part of this area is much less dissected



Great
Plains.



than the Mt. Carrizo region?



Make a cross section of the country on a line between Gognac

in the southeast corner, and Edwin about twelve miles to the northwest. What is the general

topography of the country as shown by this cross section ?

135



This is typical of wide expanses

of the Great Plains. Why is there much greater dissection in the northern part of the sheet ?



What effect has this greater dissection on the course of the roads?

What is the significance

of the small areas inclosed by saw-edged brown lines (Fig. 20) ?



Human How does this region compare in density of population (as indicated by roads and towns)

occupation

in Central w i tn that of the Mt. Carrizo region ?

Great

What does the scattered location of the houses suggest as

to the agricultural possibilities of this region ?

What curious relation do you note regarding

the number of houses and streets in the towns of Johnson and Kendall ?



Topog- Locate the position of the Kearney (Neb.) sheet on the United States map, and outline

raphy of with ink the area it includes. Also letter or write in the name of the sheet on the map.

the eastern What is the character of the eastern portion of Platte River, as shown by this map ?

border of r ' *

the Great

Plains.



What causes this braided channel condition ?



What is the source of the sediment supply ?



Why is it deposited in this eastern portion of the river?

What is the nature of the topogra-



136



phy to the north of the Platte River ?

To the south?



These numerous depressions and small,

low summits are the topography of a sandhill area. What is the source of the sand supply ?



What must be the prevailing wind direction?

Human What difference is shown on this sheet in the extent of continuously flowing streams

occupation

o eastern ag com p are( j to those of the Central and Western Great Plains areas ?

border. r



What does this indicate

as to the difference in climate from west to east?

What is the effect of this difference in

climate on the density of settlement?

What difference in the nature of agricultural industry,

in the western and eastern parts of the Great Plains, does this difference in density of popula-
tion indicate?



Write a short paragraph summarizing the origin and nature of the topography, and the
human occupation of the Great Plains region.



137



*



(



XXXII.— THE APPALACHIAN PLATEAU



Materials.



Purpose.



Introduc-
tory.



Location
and extent
of the
region.



For Each Student. — The contour map of the United States. The Centerpoint (W.Va.) sheet.
Colored pencils.

For General Class Use. — The Mt. Carrizo (Col.) sheet.

To study the topography and settlement in a region of elevated horizontal strata (a high plain
or plateau) where the climate is humid, and ivhich has been denuded for a long period.

The Appalachian Plateau bears the same relation to the Appalachian Mountains that the
Great Plains do to the Eocky Mountains, — that is, the Appalachian Plateau is a region of
elevated, horizontal strata, located on the inland side of the Appalachian Mountains. The
Appalachian Plateau contrasts with the Great Plains in that it lies in a humid climate, has
been denuded longer, and is made up of harder rocks than the Great Plains. (Text-book,
p. 84.)

On your contour map of the United States outline the area of the Appalachian Plateau,
as shown on the diagram map (Fig. 21). What is the size of this region as compared to that of

the Great Plains? What parts of what

states are included in it?

• What is the approximate elevation of the Appalachian Plateau?

How does this compare with the Great Plains

region ?



Color in, with ruled brown lines (as indicated by the pattern of the legend square on the
diagram map, Fig. 21), the area of the Appalachian Plateau as you have outlined it on your
United States contour map. Add the proper legend square, and mark it, Appal. Plat.
Study of a Locate the position of. the Centerpoint ( W. Va.) sheet on the United States map and out-

typical sec- ii ne w ith ink the area it includes. Also letter or write in the name of the sheet.
tion of the g et ( j own t he height of ten different hill summits from different parts of the sheet.

chian

Plateau.

a

139



How do they compare in height?



If the valleys were all filled in, what would be the

appearance of this region ?

What was the original topography of this region as suggested

by the uniform height of the hills ?



What has taken place since?



Make a cross section along a line running northwestward between the towns of Cascara
and Roberts. Use the same horizontal scale as that of the map, and let one division of the
cross-section paper equal sixty feet in the vertical scale. (This will give a cross section com-
parable (nearly) to the one made of the Great Plains.) In making this cross section it will
not be necessary to mark all the intersections of the contour lines ; those showing the eleva-
tion of the hilltops and the valley bottoms will be sufficient to give good results.

What is the form of the valley cross sections in this region as compared with those of the



Great Plains ?



How do the divides between streams compare in form in the two regions ?



What is the age stage of a region which has V-shaped valleys and ridge divides ?

Is this a more arid or more humid region

than the Great Plains? Why would greater

humidity accelerate weathering and the formation of ridge divides?



140



Human What determines the course of the roads in this region ?

occupation.



Why is this the case ?



Where are the houses and towns located ?

Why are there so few houses on the ridges and
the valley slopes?

Would this region be easier or more difficult to cross than the Great

Plains region ? If transportation is so much

more difficult, why is there a so much greater population than in that part of the Great Plains

that lies near the mountains ?



Why do extensive forests still remain in this region ?



Where the forest is cleared off is the land better suited to sheep raising or the raising of crops ?

What would be the effect of the discovery

of coal or iron on the settlement of such a region as this?



Write a short paragraph describing a plateau region in a humid climate having mature
drainage conditions ; and tell why such a region is difficult of settlement and development.



141



XXXIII. — THE CENTRAL PLAINS REGION

Materials. For Each Student. — The contour map of the United States. Caldwell (Kan.) sheet, Fargo

(N.D.) sheet, Centerpoint (W.Va.) sheet. Colored pencils.

Purpose. To study a plams region in which the erosion cycle has advanced to the old age stage.

Introduc- The Fargo and Centerpoint sheets are typical of plains regions in which the topography

tory. and drainage conditions are respectively young and mature. The Caldwell sheet of the

Central Plains province typifies a plains region where the erosion cycle has continued until

the country has acquired the characteristics of a plains region in old age. Thus the three

regions, of which these sheets are typical, illustrate the stages in the development of plains

topography from youth to old age. (Text-book, pp. 76-78 and 310-314.)

Location On your contour map of the United States outline the area of the Central Plains province

and extent as shown on the diagram map (Fig. 21). What proportion of the area of the United States
of the Cen-

province ^ oes tQ is re ^ on constitute? fc What is its

approximate elevation above sea level?

What large cities are located in the Central Plains province?

What reasons can you give to account for the great importance of this region in the develop-
ment of the country?

What is the general slope of the region?

What are its secondary slopes?

Color in, with ruled blue lines, (as indicated by the pattern of the legend square on the
diagram map, Fig. 21), the area of the Central Plains region as you have outlined it on your

143



United States contour map. Also add the proper legend square and mark it Central Plains

region.
Study of a Locate the position of the Caldwell (Kan.) sheet on the United States map, and with ink

typical sec- outline the area it includes. Letter in the name of the sheet.
tion of the In wlmt part of the Central Plains is this area located ?

Central ——————

Plains in

the south- Judging by your previous study of regions to the east and west of the

era part.

Central Plains, would this area have more or less rainfall than parts of the Central Plains to

the east? What indications of light rainfall

do you find on the Caldwell sheet?

What indications are there, however, that the rainfall

is sufficient for successful agriculture?

How many square miles of land are shown on the Caldwell sheet?

What is the highest point on the sheet?

The lowest? What is the average direction of slope ?

.__ Whatthen

is the general topography of the area ?



Make a cross section (along a north-south line) between the station Doster, on the
St. Louis, Kansas, and Southwestern Railroad, and the Sante Fe Railroad. Use the same
horizontal scale as that of the map, and let one section of the cross-section paper equal forty
feet vertical scale.

Make a profile of Pall Creek from its intersection with the St. Louis, Kansas, and South-
western Railway to its source, using the same vertical scale as in the cross section.

What are the shapes of the valley cross sections?

How do they differ from those of

the Fargo sheet?



How are they different from those of the Centerpoint sheet ?
144



How do these three regions compare as to the amount of elevation above sea level ?



By what processes of denudation might the valleys of the Centerpoint sheet be modified so
that they would resemble those of the Caldwell sheet?



Would a long time or a short time,

physiographically speaking, be required to bring about such a modification?

Why are there no swamps in the stream bottoms of the Caldwell sheet, although the

stream courses are meandering? L

What is meant by saying that a stream has reached grade ?



What is the character and outline of the divides between the streams ?



How do these differ from those of the Fargo

sheet, on the one hand, and the Centerpoint sheet on the other?



Diagram the pattern of

145



the drainage system on the Caldwell sheet, showing how a large stream is fed by tributaries,
and these in turn by smaller tributaries, and so on.



Why is such a drainage system called dendritic?

1 Is the angle between

a tributary and a main stream acute or obtuse on the upstream side?

What are the conditions on the Fargo sheet in this respect?



Human What is the pattern of the wagon roads on the Caldwell sheet ?

occupation.

Why is such a pattern possible here ? .



Do the railways attempt to follow the lines of the divides or of the stream valleys ?

Are the bends in the course of the Wichita

and Western division of the Missouri-Pacific Railroad necessitated by the topography,



or by a desire to touch at every small town ?



.__ Why would such a course be impossible on
146



the Appalachian Plateau ?



What determines the location of towns in the region of the Caldwell sheet ?



Why have some towns grown to a larger size than others?

No houses are plotted on

this sheet. Would you infer from this that this is a sparsely settled region?

What do the number of small towns, the number and pattern

of the roads, and the number of railroads indicate in this connection?



Write a short paragraph comparing and contrasting the topography, drainage, and
human occupation in plains regions in youth, maturity, and old age, as studied in this and
the preceding exercises.



147



c



XXXIV. —THE AREA OF CONTINENTAL GLACIATION IN THE UNITED STATES



Materials.



Purpose.



Introduc-
tory.



Location
and extent
of the area
of conti-
nental gla-
ciation in
the United
States.



For Each Student. — The contour map of the United States. The Whitewater (Wis.) sheet,
the Caldwell (Kan.) sheet.

To gain an appreciation of the area of the United States that was affected by the continental
glacier daring the glacial period; and to study a portion of the glaciated area where the effects of
the ice advance and retreat were very pronounced.

In the preceding exercises, plains regions, whose structure was in every case horizontally


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Online LibraryRalph S. (Ralph Stockman) TarrA laboratory manual for physical and commercial geography → online text (page 7 of 16)