Jerbourg Point - people have lived on this point since Neolithic times and then during the Bronze Age and the Middle Ages. Thus, it has a long history of housing and defensive systems in the form of mounds and ditches, given its strategic position. Along the narrowest part of the isthmus of the Jerbourg promontory are earthen ramparts, designed as a defensive camp or fort. According to Gustave Jules Dupont in Histoire du Cotentin et de ses iles 1870, "they begin on the west side, at the top of the cliff, at the beginning of the path leading from Petit-Port. Of the three embankments, the deepest is the outer one, about 8 ft. 2.4 m. The embankments extend to the Doyles Monument. The three embankments are located on the eastern slope, with the northern two close together. Flint fragments, arrowheads, Celtic pottery, stone axes, müllers, and an unfinished doublet -headed stone hammer, of which a flint arrowhead is preserved in the Guy-Alles Museum.
Pottery has been found in various parts of Jerburg Point. Stone tools, flint knives, and 10 arrowheads from the Late Neolithic/Early Bronze Age, 2000 B.C. period were found in earthen ramparts that extend from Portel Bay in the west to La Bate de Muir near Le Bie du Nez. The ditch was created using a natural fault line through the narrowest part of the Djerburg Peninsula, which is about 400 m wide at this point, terminating on both sides with cliffs steep enough to not need protection from the flanks, with a base on the cliff. There is an inner bank, originally about 3 m high, which lies on the rock and is lined with clay-bound stones.
The Roman hoard, dating to the late 3rd century, was discovered in the 19th century and contained 68 tetradrachms minted in Alexandria during the reign of the emperors Probus 4, Carus 3 coins, Numero 3 coins, Carinus 4 coins, Diocletian 34 coins and Maximian 19 coins.