Sechin Alto Principal Platform
Sechin Alto · Sechin Alto Main Mound · Casma Sechin Alto Pyramid · Principal Platform Sechin Alto
Initial Period (Casma/Sechin, 1800–900 BCE, peak 1500 BCE)·Casma–Sechin culture (Initial Period, Casma Valley)·🇵🇪 Ancash Region, Casma Valley 12 km inland from Pacific, Sechin–Moxeque complex, Peru
About
About Sechin Alto Principal Platform
Largest Formative Period platform in Americas (1800–900 BCE, Initial Period peak 1500 BCE): principal mound 300×250 m base, 44 m high with two lateral broad platforms forming U around plaza 300×250 m facing northeast, with four atriums. Stone facing with mud mortar and plastered floors; associated Sechin Alto Complex 2 km north includes Cahuachi-style geoglyphs later? Part of Sechin-Casma complex with Moxeque (Moxeke) opposite valley. Built by Casma culture before Chavín. Pozorski 1980s–2000s survey. No pottery in earliest phases (Preceramic tail).
Why it mattersLargest Initial Period mound in Americas (larger volume than Great Pyramid before erosion); type-site for Casma-Sechin polity before Cupisnique-Chavín.
Open questions
Mysteries & theories
Mysteries
- 01Labor mobilization without central state — corporate collective vs chiefly
- 02Why U-shape facing northeast sunrise
Theories
- 01Sechin Alto as corporate polity capital absorbing Moxeque after valley rivalry
Theories are interpretations, not findings. The seal above tells you how much scholarly weight the place carries.
History
How it came to be
- Built
- c.1800–1500 BCE principal platform built; atriums c.1400 BCE
- Period
- Initial Period (Casma/Sechin, 1800–900 BCE, peak 1500 BCE)
- Culture
- Casma–Sechin culture (Initial Period, Casma Valley)
- Purpose
- Largest Formative platform and U-plaza center — Casma valley chiefly capital before Chavín influence
- Excavation
- Partially excavated
c.1800–1500 BCE principal platform built; atriums c.1400 BCE
Initial construction / foundation
c. 1200–600 BCE
Major use phase and refurbishment
20th century
Modern archaeological survey and excavation
On the ground
Structures & features
9.4580° S · 78.3210° W · 42 m · 3 mapped features
Principal platform
pyramid300×250 m mound 44 m high with three construction phases
9.4580° S · 78.3210° WNortheast atrium complex
atriumFour sunken atriums facing northeast U-plaza
9.4575° S · 78.3205° WPlaza and lateral platforms
plaza300×250 m plaza with lateral arms 150 m
9.4585° S · 78.3215° W