was seen all through in red colour only. Similar arches were seen when the Moon was rising. Such a phenomenon was noticed by the survey team frequently on the mountains here. In the past, others had also observed this phenomenon and named it as the "frostbow" or "cloudbow" as the cloud vaporized with sun rise. They are also called it the White rainbows unlike the rainbows which formed after rains. Culture The Pambamarca Fortress Complex is a large installation of many Inca pucarás, located on the peaks and ridges of the extinct Pambamarca stratovolcano. During the current research by the Pambamarca Archaeological Project, the team uncovered pre-Inca fortresses at the base of Pambamarca. The existence of two types of forts and the recovery of many armaments is suggestive of a pre-Columbian borderland, which is an important and rare find in New World archaeology. Another culture of special importance, which attracted the Incas to this region is that the mountains are located on the equatorial line. It is the unique feature not replicated anywhere else in the world and forms the dividing line for the culture. The mounds found here have been used by the local Indians as landmarks for solar and star position calculations. Archeological finds The Incan Forts discovered in the Pambamarca extinct volcano region are 20, apart from two fortresses built by the Cayambe, the ethnic people of Ecuador. These fortresses have been identified as about 500 years old. According to the Director of the Archaeological Project these are inferred to represent border region between the fortresses built by the Ecuadorian people and the Inca. More fortresses are likely to be found in the entire northern region of Ecuador, which need further explorations. The Inca forts located at about elevation on ridges were built with stones laid over plinths called ushnus. Archeologists have inferred that these forts were inhabited and people living in them were ready for fighting with stone slings kept ready for use. The two Cayambe forts built with strong volcanic material known locally as cangahua are of large size which were inhabited. The forts were also well stocked with ammunition of two types-sling stones and bola stones. References External links Photos Pambamarca Archaeological Project website Pambamarca Archaeological Project photos Stratovolcanoes of Ecuador Geography of Pichincha Province Archaeological sites in Ecuador Pleistocene stratovolcanoes