On the ground, most of the lines are formed by a shallow trench with a depth between 10 and 15 cm (4 and 6 in).

Such trenches were made by removing the reddish-brown iron oxide-coated pebbles that cover the surface of the Nazca Desert.

They were designated as a UNESCO World Heritage Site in 1994.

The high, arid plateau stretches more than 80 km (50 mi) between the towns of Nazca and Palpa on the Pampas de Jumana, about 400 km (250 mi) south of Lima.

Determining how they were made has been easier than finding why they were made.

Scholars have theorized the Nazca people could have used simple tools and surveying equipment to construct the lines.

The team has been doing field work there since 2006 when it found about 100 new geoglyphs.

Archaeologists, ethnologists, and anthropologists have studied the ancient Nazca culture to try to determine the purpose of the lines and figures.

Scholars differ in interpreting the purpose of the designs but, in general, they ascribe religious significance to them.

Because of its isolation and the dry, windless, stable climate of the plateau, the lines have mostly been naturally preserved.

Archaeological surveys have found wooden stakes in the ground at the end of some lines, which supports this theory.