Jord: Giantess of Earth and Mother of Thor

Although Thor is now among the most famous Norse gods and he was also the son of Odin, he was not the one who inherited Odin's throne. Because the only son of Asgard's chief king and the queen was Baldur the Shining God. Thor, instead, was the son of Jord, a giantess living in Jotunheim. 

Jord was an obscure figure in Norse mythology. She was seldom mentioned through the myth. 

Jord was a giantess in Norse myth. She was the giantess of earth who embodied the quality and strength of earth. There were few things we learn about this figure: she was the mother of Thor and the daughter of Nott (Night).

Jord the giantess of Earth in Norse mythology

In one version, Jord was described as the rival of Frigg, the only queen of Asgard and also the wife of Odin. 

In the Prose Edda by Snorri Sturluson, the manuscript reads:

The splendid hater of the fire of the sea defends the beloved of the enemy of the wolf; ships’ prows are set before the steep brows of Mim’s friend’s wife. The noble mighty-ruler knows how to hold the serpent’s attacker’s mother. You who torment necklaces, enjoy the troll-wife’s enemy’s mother until old age.

If you haven't learnt about Norse kennings, we bet you cannot understand what the version tried to say. The explanation of the mentioned verse is an interesting thing to read though. 

What we try to say here is the mention of Jord. It said the "serpent's attacker's mother". 

Who was the famous serpent attacker in Norse mythology? It was Thor who fought with Jormungandr the Midgard Serpent in Ragnarok. So Thor's mother was Jord and Jord was the giantess of earth. 

"The noble mighty-ruler" refers to the reigning king at that period. So it simply meant "The true king knows how to protect his land".