Creating and Analyzing a Phoenician Navigational Safety Zone

Introduction

How would you use land visibility to map an ancient civilization's navigational safety zone?

The Phoenicians excelled at maritime trading, sailing the Mediterranean Sea between 1500 and 300 AD (Markoe 2000). These remarkable seafaring people, credited with spreading the alphabet, occupied small enclaves in port towns that served as their bases of operations both religious and economic. These ports of call defined the Phoenician geographic footprint and grew to include many locations along hundreds of kilometers (km) of the eastern Mediterranean coast. Sailing safely from port to port was essential to the Phoenicians' livelihood.

Navigating within sight of land is the safest way to sail and remained the Phoenicians' preferred method, even when navigation using celestial bodies became better understood. Exactly how far out to sea could they sail and still be in sight of land? In other words, what was the Phoenicians' navigational safety zone? Landmark visibility while at sea depends on the coastal land's height above sea level (elevation), the distance of inland elevated features from the coast, and air clarity. Using a digital elevation model (DEM), observer point locations, and parameters available in geographic information system (GIS) software, you can model this landmark visibility and map the navigational safety zone within which an enterprising ancient people sailed for more than a thousand years.

Location

Eastern Mediterranean Sea

Time to complete the lab

Two hours

Prerequisites

Cursory familiarity with ArcGIS software

Data used in this lab

Shuttle Radar Topography Mission (SRTM) 90-meter (m) elevation data; country and ocean boundaries; latitude and longitude locations

Geographic coordinate system: WGS 1984

Datum: WGS 1984

Projected coordinate zystem: UTM Zone 36N