It mainly comprises gray, silty and micaceous shale, containing interbeds of fine-grained sandstone, siltstone and sandy limestone.

Deschaillons owes its name to Lord Pierre de Saint-Ours,[6] who obtained from the King of France this concession located on the banks of the St. Lawrence River.

St. Lawrence River Deschaillons origins can be traced back to the seigneurial concession obtained on April 25, 1674, by the Knight Pierre de Saint-Ours.

[7] During the first years, the Lord of Saint-Ours granted land for clearing and agricultural exploitation to around twenty settlers, some of whom had appellations still present in the village as surnames (Auger, Barabé, Beaudet, Mailhot, Tousignant...).

[8] During the first three centuries, the development of agriculture, livestock breeding, navigation and, later, the establishment of several brickworks made possible thanks to the clayey soil along the banks of the river constituted the main economic activities of Deschaillons-sur-Saint-Laurent.

Due to its unusual geographical positioning (a riverside village with land majestically overlooking the St. Lawrence River), Deschaillons is a popular vacation spot that welcomes a few hundred additional residents every summer, including thanks to the abundance of seasonal chalets, a large campsite (Cap à la Roche), and a lodge/chalets estate (Le Domaine d'Eschaillons).

Primary school, “Métro” food market, convenience (dépanneur) store/gasoline store, cheese factory, pharmacy, veterinary clinic, municipal multi-functional centre (former church), (former) presbytery, post office, car dealership, mechanics and auto body shops, hair salons, restaurants, maritime lighthouse, savings and credit union bank, artisanal production cooperative, four (4) public charging terminals for electric vehicles (EVs), ecocentre, fire station and first responders.

Pamphile Le May, novelist, poet, storyteller, librarian and lawyer, lived the last years of his life in Deschaillons, from 1912 until his death on June 11, 1918.