That's a new wrinkle. I had not thought of that before. Here is Wikipedia's explanation of Caucasoid physiology; from this you can imagine that Caucasians may have crossed over into Alaska or made their way west into the Euro-Atlantic islands:
"Caucasoid race" is a term formerly used in physical anthropology to refer to people of a certain range of anthropometric measurements. Conceived as one of the "great races", alongside Mongoloid and Negroid, it was taken to consist of a number of "subraces". The Caucasoid peoples were usually divided in three groups on linguistic grounds, termed Aryan (Indo-European), Semitic (Semitic languages) and Hamitic (Berber-Cushitic-Egyptian).
The postulated subraces vary depending on the author, including but not limited to Nordic, Mediterranean, Alpine, Dinaric, East Baltic, Arabid, Turanid, Iranid and Armenoid subraces.
19th century classifications of the peoples of India considered the Dravidians of non-Caucasoid stock as Australoid or a separate Dravida race, and assumed a gradient of miscegenation of high-caste Caucasoid Aryans and indigenous Dravidians.
By contrast, Carleton S. Coon in his 1939 The Races of Europe classified the Dravidians as Caucasoid as well, due to his assessment of what he called their "Caucasoid skull structure" and other physical traits (e.g. noses, eyes, hair). In his The Living Races of Man, Coon stated that "India is the easternmost outpost of the Caucasian racial region". Sarah A Tishkoff and Kenneth K Kidd state: "Despite disagreement among anthropologists, this classification remains in use by many researchers, as well as lay people."
There was no universal consensus of the validity of the "Caucasian" grouping even within scientific racism. Thomas Henry Huxley in 1870 wrote that the "absurd denomination of 'Caucasian'" was in fact a conflation of his Xanthochroi and Melanochroi types.
In 1920 H.G. Wells referred to the Mediterranean race as the Iberian race . He regarded it as a fourth subrace of the Caucasian race, along with the Aryan, Semitic, and Hamitic subraces. He stated that the main ethnic group that most purely represented the racial stock of the Iberian race was the Basques, and that the Basques were the descendants of the Cro-Magnons.
Europaeid types
Here they are. Personally, I think the Celts should be their own type: