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Site Catchment and Viewshed Analyses: Interacting with the Landscape

Relationship of Fortress and Landscape

• Severe wind erosion leaves fortresses in shambles

• How do you study fortresses then?

• ANSWER: The landscape!

• Landscape unchanged in past 500 years

• Fortresses take defensive landscape into account

Study Area: Ecuador Highlands

• Darker colors on the map represent higher elevations

• The Caranqui centered in enclosed Cayambe Valley

• The Inka maintained settlement behind forts at El Quinche

Why Here? Understanding the Location of the Pambamarca Fortress ComplexEric Dyrdahl

Department of Anthropology, Northwestern University

Introduction

By the end of the 15th century CE, the Inka Empire stretches to Quito, Ecuador. Most smaller polities the Inka threaten choose to submit to Inka rule willingly1, but a confederation of chiefdoms north of Quito, the Caranqui, resists Inka rule to produce an uncommon situation2. The Inka are forced to engage in a prolonged conflict and build the Pambamarca fortress complex3.

The Pambamarca Fortress Complex is unique…• The Inka rarely built fortresses4

• Conquest warfare largely ignored due to ritual warfare5

• These 13 fortresses constitute the largest fortification cluster ever built by the Inka6 (see map below)

Research QuestionWhy did the Inka build the Pambamarca fortress complex where they did?

HYPOTHESIS: Inka chose this location because they could subsist off nearby resources AND follow the Caranqui’s actions

No Maize = No Caranqui• Caranqui’s main food was maize8

• Areas where maize could be grown are in yellow, while red represents areas where it cannot be grown

The fortress complex is one of the few places where maize cannot grow

Methodology: A GIS-based Approach

• Geographic Information Systems (GIS), a computer software program, used to answer research question

• Two data sets used: computerized elevation model and global positioning system (GPS) points taken at sites in the field• Site Catchment Analysis: draw 1 km circles around each site to examine elevation bands near each site

• Each elevation band represents different crops that could be grown • Six known domesticates in Andes: maize, common bean, potato, mashwa, quinoa, ulluco7

• Pambamarca forts compared to Rumicucho (another Inka fort nearby), Caranqui forts, Cayambe, El Quinche, and complete study area

• Viewshed Analysis: use elevation model in 3-D analyst to determine what could be seen from each fortress

Andean Domesticates: Pambamarca Elevation Band Percentages Unlike Any Other Site

Viewshed Analysis: Panoramic View of the Cayambe Valley, But Not Forts

• 3-D image on left shows what is visible from the central fortress of the complex

• Blue = visible from fort

• Tan = not visible from fort

• Map on right shows entire fortress complex from above

• Notice that while the entire Cayambe Valley is visible from the central fort, the two forts directly on route to valley cannot be seen

El Quinche

Cayambe

Caranqui

Forts

Pambamarca

Fortress Complex

The Inka Chose to Build Here Because…• Could subsist off tubers with supplements (especially maize) from El Quinche

• Tight clustering of forts suggests they were protecting the landscape

• Supported by ethnohistoric works9

• Can see entire Cayambe Valley and follow any moves by the Caranqui

• Fort-to-fort communication not done by sight (likely through trench)

• Few Caranqui in area since maize cannot be grown here

• Powerful location for religion10

Limitations/Future Studies

• Cannot conduct plant studies (erosion)

• Hard to determine which factor was the most important in selection process

• Begin similar studies of other forts both in the Andes and elsewhere that highlight conquest warfare

References Cited1Rowe, J.1946 Inca Culture at the Time of the Spanish Conquest. Handbook of South American Indians. Vol. 2. Ed. J. Steward. Washington: United States Government Printing Office. 183-330.2Connell, S.V. and C. Gifford2003 National Science Foundation High-Risk Research Proposal. Proyecto Arqueológico Pambamarca.3Oberem, U., W. Wurster, R. Hartmann and J. Wentscher 1969 La fortaleza de montaña de Quitoloma en la sierra septentrional del Ecuador. Boletín de la Academic Nacional de Historia 114: 196-205.4D’Altroy, T.N.2002 The Incas. Malden: Blackwell Publishing.5Arkush, E. and C. Stanish2005 Interpreting Conflict in the Ancient Andes: Implications for the Archaeology of Warfare. Current Anthropology 46 (Feb. 2005): 3-28. Northwestern University Library. 26 May 2006 <www.library.northwestern.edu>.6Hyslop, J.1990 Inka Settlement Planning. Austin: University of Texas Press. 7Moseley, M.2001 The Incas and their Ancestors: The Archaeology of Peru. London: Thames and Hudson.8 Athens, S.J.2003 Inventory of Earthen Mound Sites, Northern Ecuador. Honolulu: International Archaeological Research Institute.9Cobo, B. 1979 [1953] History of the Inca Empire: an account of the Indians' customs and their origin, together with a treatise on Inca legends, history, and social institutions. Austin: University of Texas Press. 10Gasparini, G. and L. Margolies 1980 Inca Architecture. Trans. P. Lyon. Bloomington: Indiana University Press.

Andean Domesticates Within 1 Km of Each Site

8.24

57.75

21.02

67.88

14.29

3.69.386.77 2.22

8.84

0

20

40

60

80

100

All ExceptUlluco (1339-

3350)

All ExceptMaize (3351-

3700)

Potato, Quinoa,Ulluco (3701-

3830)

Quinoa (3831-3878)

No KnownDomesticates(3879-5548)

Crops That Could Be Grown (Elevation Band in Meters)

Pe

rce

nta

ge

of

Ca

tch

me

nt

Cir

cle

Indigenous Forts Rumicucho Pambamarca Forts

Complete Study Area Cayambe El Quinche

Tuber crops could easily be grown by Inka in these bands

Pambamarca forts are only sites with less than 100% of catchment in this band

3-D Viewshed From Central Fort Map of Fortress Complex

Cayambe Valley

Two Inka forts on route to

the valley

Two Inka forts on route to valley

Central fort from which viewshed was examined