In Petronius's Satyricon, two characters are discussing changing their appearance to hide their appearance. Among other suggestions (circumcising themselves to look like Jews, and piercing their ears to look like Arabs) is the suggestion that they could appear as Gauls if they were to cover their faces in chalk.
Does this imply that the Roman perceived Gaulish peoples as being particularly pale in complex, or did Gauls have some kind of practice that would denote that they covered their face in chalk for some purpose?
The Romans conventionally described Gauls, Britons, Germans, and other uncouth and beer-swilling northerners as pale. This was blamed on the wretched climate in which they lived. As Pliny the Elder reports:
"There can be no doubt, that the Ethiopians are scorched by their vicinity to the sun's heat...while, in the opposite and frozen parts of the earth, there are nations with white skins and long light hair." (2.189)
The stereotype crops up in Petronius and many other Roman authors. Northerners are typically tall, often overweight (they were thought to have poor self-control), and invariably pale. If they linger in southern climes too long, in fact, they tend to get sick from all the sun and heat. Florus, for example, claims that:
"The Insubrian Gauls, who also dwelt near the Alps, possessed the spirit of wild beasts and stature greater than human, but, as experience proved....[their bodies] reared in a moist climate, have a certain similarity to our own snows, for as soon as they become heated in the fray, they immediately break into sweat and are dissolved by light exertion, as snow is melted by the sun." (1.20)
So, no surprises here. The Romans just thought that the Gauls were pasty.