Geology versus Agglomeration: Bedrock
Depth and the Formation of the Manhattan
Skyline, 1890-1915
Jason Barr, Rutgers U.
Troy Tassier, Fordham U.
Rossen Trendafilov, Fordham U.
Outline of Talk
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
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The “Debate”: Geology and the Spatial Distribution of Activity
Summary of Conclusions
Manhattan:
 Skyscrapers: 1890-1915
 Geology and geography
 The “Great Leap”
Results
 Costs
 Location Choices
 Some evidence on workers residence locations
Extras (if time)
 Pictures
 Some Geological History
The Skyline
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Why do we observe two clusters of
skyscrapers in Manhattan and not one
continuous one?
Why did builders “jump” from downtown to
midtown?
What role did bedrock play in the location of
skyscrapers?
How sensitive were building decisions to
changes in bedrock depths?
Causation or Correlation?
“[N]ear New York University, the surface bedrock drops
appreciably—up to several hundred feet below the street
level. Farther south…it comes again to within about one
hundred feet of the surface. Dividing Manhattan into the
‘downtown’ and ‘midtown’ districts….That is to say, the
skyscrapers of New York City are clustered together into
the midtown group, where the bedrock is within several
feet of the surface, and the downtown group, where the
bedrock again reappears to within forty feet of the
surface near Wall Street. In any event, it is readily seen
how clearly the accessibility of the bedrock has, to some
degree, controlled the architectural planning of the city.”
From The Geology of New York City and Environs, C. J. Schuberth © 1968, pps. 8182. Emphasis added by me.
Conclusions
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Depth to bedrock appears to have had, at
best, a modest effect on the distribution of
skyscrapers.
Some evidence of bedrock effect within
downtown.
Jump was driven by:



Transportation hubs.
Avoidance of dense residential and manufacturing
districts.
Readjustment to be near white collar workers.
Manhattan
Geology
Manhattan Skyscrapers and Nonskyscrapers (1915)
Skyscraper Technology
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Here skyscraper: 80 meters or taller (about 20
stories).
First NYC skyscraper 1889: 11 stories.
Pulitzer World Building (1890), 20 stories, 94
meters.
Steel skeleton.
Elevator with safety break.
Caissons to anchor building to bedrock.
Skyscrapers and Bedrock


After a certain height, a building had to
be anchored to bedrock so as to
prevent (possible uneven) settling.
If two buildings have the same total
area, but one had three stories and the
second had 20 stories, only the second
building would need to be anchored.
Skyscrapers Statistics, 1890-1915
Depth to Bedrock (1915)
nonskyscrapers
skyscrapers
Depth to Bedrock (Meters)
50
North
100 feet
40
14th St.
30
Bow ling
42nd St.
Green
Central Park
South
20
Canal St.
10
City Hall
0
40.70
40.71
40.72
40.73
40.74
40.75
40.76
Latitude (Degrees)
40.77
Building Heights and Bedrock Depths
Relative to Street Level
Avg. Relative Building Height
Avg. Relative Bedrock Depth
80%
=>=>=North=>=>
50%
20%
-10%40.706
40.708
40.711
40.715
40.719
40.725
40.732
40.739
40.744
40.752
40.755
-40%
Latitude (Degrees)
-70%
“100 feet”
-100%
40.763
The “Great Leap”: Location of
Skyscrapers over Time
Latitude (degrees)
40.77
40.76
40.75
40.74
40.73
40.72
40.71
40.70
1890
1895
1900
1905
1910
Year
1915
Population Movement: Manhattan
Residents above 40th Street
Pop
%Pop
1,400,000
60%
1,200,000
50%
1,000,000
40%
800,000
30%
600,000
20%
400,000
10%
200,000
0%
0
1860
1870
1880
1890
1900
1910
Demographic Locations, 1890
% White with two native parents
% Foreign
Bedrock depth
65
45
25
5
40.7
-15
-35
-55
40.71
40.72
40.73
40.74
40.75
40.76
40.77
The El’s (1890): # El’s w/in ½ mile
radius of each lot
14
City Hall
12
14th St
10
42nd St
8
6
4
2
0
40.705
40.715
40.725
40.735
40.745
40.755
40.765
Model Description

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Office-based firms have a demand for height, where height
(space) is input into production.
Demand is function of agglomeration benefits and office rent.
Developers supply height based on office rents and cost of
construction
Equilibrium height is function of agglomeration effects and cost
of anchoring to bedrock.
h  h A j , c j 
*
 Pr(h  h | x)  Gxβ
*
Example: Agglom. Benefits Large,
Bedrock Costs Larger
Building
height
Bedrock not relevant, as
agglom. benefits fade
away
Building
height
Bedrock a barrier
hbar
hbar
Distance from Center
Distance from Center
Construction Cost Data



Fuller Construction Company
53 large commercial projects in
Manhattan, 1899-1915
Data Collected:

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Total Construction Costs
Depth to Bedrock
Building Height
Building Volume
Index of Brick Costs
Construction Costs Descriptive
Stats.
Regression Results
Cost Effects



Bedrock costs not relevant (even negative) for
smaller projects. For larger projects, only a small
fraction of total building costs.
Differences in land prices between the financial
district and the bedrock valley were several hundred
thousand dollars.
A skyscraper could have been built more cheaply in
the bedrock valley than in the financial district when
you consider the net effect of additional bedrock
costs and land acquisition costs.
Cost Effects



For median skyscraper (21 stories), additional meter
down increases costs by about $650 per meter.
A 1 st. dev. change in depth to bedrock from the
average adds about ½%.
Largest skyscraper (32 stories) increases construction
costs by about $9,000 for each 1 meter increase in
the bedrock depth (7%).
Spatial Distribution: Data

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Skyscrapers: skyscraperpage.com & emporis.com
Non-skyscrapers: randomly chosen lots.
Heights checked against 1921 Land Book for
Manhattan.
Bedrock: (1) Boring maps, (2) USGS contour maps.
Population and Worker Density: Federal and State
Censuses.
Land Values and Assessed Values: Reports from the
Tax Commissioners of NYC.
Elevated Trains: El Maps from 1890.
Demographics: 1890 Census.
Sanitation
Districts,
1890
Spatial Distribution: Data &
Descriptive Statistics
1 hectare = 2.5 acres
Probit Results: Marginal effects on prob. of
skyscraper on given plot of land
Predicted Probability of Skyscraper holding bedrock
constant
1.0
0.8
0.6
0.4
0.2
0.0
40.700
40.710
40.720
40.730
40.740
40.750
40.760
Latitude (degrees)
40.770
Difference in Predicted Probabilities with and
without Bedrock Variable vs. Latitude (Pred P
with BR - Pred P w/o BR)
0.15
0.10
0.05
0.00
40.71
-0.05
40.71
40.71
40.72
40.73
40.74
40.74
40.75
40.76
latitude (degrees)
-0.10
-0.15
Latitude (degrees)
Trow’s NYC Directory, 1892

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Collected data on job and home address
for 5000 workers.
4878 were living in Manhattan.
Created job categories (in part based
on 1890 census).
Trow’s NYC Directory, 1892
Job Category
Manufacturing
Domestic service
Transportation
Clerk
Sales
Professional service
Protection
FIRE
Agents and Collectors
Peddlers
Managers and Foreman
Total
Freq.
1,724
667
582
577
503
354
154
98
87
80
52
4,878
Percent
35.3
13.7
11.9
11.8
10.3
7.3
3.2
2.0
1.8
1.6
1.1
100
Trow’s NYC Directory, 1892
Top 10 Jobs
Rank
1
2
3
4
5
6
7
8
9
10
Job
Freq.
Clerk
577
Laborer
361
Tailor
254
Driver
226
Carpenter 167
Painter
122
Engineer
108
Lawyer
90
Cutter
88
Smith
87
Percent
11.8
7.4
5.2
4.6
3.4
2.5
2.2
1.9
1.8
1.8
Distribution of Sample
Location of
skyscrapers
1890-1915
Location of workers
in Finance,
Insurance and Real
Estate (FIRE)
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Workers in
Manufacturing Jobs
Conclusions Regarding
Bedrock Effect
H1: Insurmountable barrier after some depth.
Refuted by scatter plot.
 H2: Economically not viable after some point
Refuted by cost regressions.
 H3: Tipping Point Effect
Refuted by predicted skyline based on
holding bedrock constant.
 H4: Little or No Effect.
Consistent with regressions and predicted
skyline.

Conclusions

Readjustment to new spatial
equilibrium: “Edge City” formation.




Population Movement.
Factory and Slum “flight.”
Transportation Hubs.
Other Economic Factors.
Appendix I: Pictures
Tribune Building (1875)
“The brick piers of the exterior
walls had to be enormously thick in
the lower part of the building to
bear the weight of the stories
above.” (Landau and Condit)
“The nine-story height insured that the
tower would be taller than any existing
New York office building and was thus
neither an arbitrary choice of height nor
one based on the functional space
requirements of the newspaper. The design
of the Tribune building was primarily
governed by the enhanced public image
that would be garnered for the newspaper
and only tangentially by the potential
economic benefits of building tall” (Wallace
2006)
Home Insurance Building (1885), Chicago
10 stories of 138 feet (42 m)
The Tower Building (1889):
New York’s first “skyscraper”
11 Stories
Ego or Economics?

Cass Gilbert: The skyscraper “is a
machine that makes the land pay”
(ER,
1900).

F.W. Woolworth: “I do not want a
mere building, I want something that
will be an ornament to the city'' (NY
Times, 1910).
Pulitzer’s World Building, 1890
20 stories, 94 meters
The Flatiron (1902),
22, 87 meters
NY Times Building (1904)
25, stories, 111 meters
Woolworth Building (1913)
57 stories, 241 meters.
Equitable Building (1915)
40
Stories,
164
meters
Appendix II: Geological
History



500 MYA: NYC bedrock began as muds
and sands deposited in the Iapetus
Ocean (off coast of what is now N.
Am.).
Due to compaction they became
sedimentary rocks.
440 MYA: Plate tectonics closed this
ocean; massive island chain collided
into N. Am.
Geological History Cont.



Sedimentary rocks became folded and
deformed and were buried deep within
a mountain range called the Taconic
Mountains (akin to Himalayas).
Mountain range weight metamorphized
sedimentary rock to schist and gneiss.
Erosion has worn these mountains away
leaving current bedrock.
The Last Ice Age
During the Pleistocene epoch (the Ice Age:
about 1.8 million years ago to 8,000 years
ago), large ice sheets bulldozed the
landscape. Rocks within the glaciers
scraped and scratched the bedrock of
Central Park producing long linear
striations and grooves. Long Island is
composed of rubble that the glacier left
behind as it melted.
http://research.amnh.org/eps/nycgeology