The additional sudden change is the lack of population. Hamlets are few and far between. I still follow the old Camino Real, but sometimes with 25 kilometers or more between houses and drinking water. A few scraggly cows and horses keep me company; the guinea pigs have been replaced by lizards scurrying beneath the underbrush. Endless chatty birds.
Continuing along with the crappy map of Argentina, one dot looks like the next, though the legend says 0 to 1,000 inhabitants... in most cases, the population of the dot is on the 0 end of the scale. Ghost towns around old railroad stations. In San Luis, a provincial city of a few hundred thousand, an energetic parish priest insisted that I stop the next night in a village with another one of his 5 churches. I was reluctant, being only 30 kilometers away, until he mentioned the thermal waters there. Hard to find sweeter words to fill the ears of a pilgrim. And me, a VIP (verily intrepid pilgrim?), had a long hot soak for my feet and the rest of me, sunburnt arms and all... it's great when these little gems reveal themselves, like cherries popping up right in front of you and getting surprise bonus points in the Super Mario Brothers game of life =)