Contrary to what Marvel claims, Frigg is not Thor’s mother. This honor belongs to a benevolent giantess named Jörd.
Jörd is cited in the Prose Edda and the Poetic Edda. She is Mother Earth, the Goddess who is the earth herself.
Moder Jord scuplture by Stephan Sinding, Vejen Art Museum Denmark
Her name seems to be related to mountains and the physical terrain of the earth mass. You walk upon her, live in a dwelling constructed of her: she is inescapable, immanent, all around. She is the divine that is the world, herself.
Author Rudolf Simek argues that Jörð is also known for another name: Fjörgyn.
Fjörgyn also means earth, and the name is quoted in the Völuspá, in the kenning "Fjörgyn’s son" for Thor, and in Hárbarðsljóð as the mother of Thor.
Jörð is the daughter of Nótt (Night) and Annar, both primordial Jötnar. She is the mother of Thor and another God named Meili, by Óðin.
Jörð herself is a jötunn, one of the elder race of giants. She is depicted as a benevolent deity, sometimes placed amongst the Aesir, who receives veneration in modern North pagan practices.
One of the distinguishing traits of the Jötnar is that they tend not to care for, and are even hostile towards, humankind. The Jötnar counted among the Gods of Ásgard are those who, like the Gods, care for and watch over us. Interestingly, there are said to be nine Jörð-like giantesses, one for each of the Nine Worlds. Whether Jörð has eight sisters, or whether the ancient Norse people were aware of the other planets in our solar system, or whether Jörð exists inter-dimensionally, is not known.
It is comforting that Thor, protector of humankind, is the son of Mother Earth herself. It does leave a feeling that the very planet we inhabit cares for us and want us, as a species, to thrive. Hail Jörð!
Sources:
Simek, Rudolf. 2007 (1993). Translated by Angela Hall. Dictionary of Northern Mythology. D.S. Brewer. ISBN 0-85991-513-1
Orchard, Andy. 1997. Dictionary of Norse Myth and Legend. Cassell. ISBN 0-304-34520-2
Jesse Byock (2005) Snorri Sturluson, The Prose Edda. 1st. edition. London, England: Penguin Books Ltd. ISBN-13 978-0-140-44755-2
Faulkes, Anthony. Edda. Trans. 1982. Oxford University Press. ISBN-13: 9781389651922
