After learning of the favourable conditions that Serrano found at Santa Cruz, Ferdinand Magellan decided to move the fleet there from St. Julian, where they had stopped to overwinter, around August 24.

[3] By the start of April 1834, HMS Beagle had reached a stage in its survey voyage where minor repairs were needed to its keel and copper sheathing, so Captain Robert FitzRoy chose the river as a suitable place to lay the ship ashore.

While this work was carried out, FitzRoy led an expedition upriver with aim of finding its source, 300 kilometers (186 mi) distant in the Andes.

Darwin was greatly impressed by the series of stepped plains of pebbles which would have formed over long periods in the sea, and went against Lyell's ideas of continuous gradual development by implying an intermittent process.

When Darwin described this in his book on South America's geology, he wrote "I think we must admit, that within the recent period, the course of the Santa Cruz formed a sea-strait intersecting the continent.

[4] In his Journal of researches, p. 218, Darwin criticised the catastrophism proposed by former geologists who, in trying to explain the erosion of the lava and other rocks of the valley, "....would have brought into play, the violent action of some overwhelming debacle; but in [the case of the Santa Cruz] such a supposition would have been quite inadmissible; because the same step-like terraces, that front the Patagonian coast, sweep up on each side of the valley.

The expedition ended due to lack of supplies and turned around, had they gone a bit further they would have discovered that the source of the river valley was the glacial lake Lago Argentino at the foot of the mountain.

The valley in this upper part expanded into a wide basin, bound on the north and south by the basaltic platforms, and front by the long range of the snow-clad Cordillera.

This, although really enough for reasonable men, was, after a hard day's march rather scanty food: a light stomach and an easy digestion are good things to talk about, but very unpleasant in practice.