Sides: בְּיַרְכְּתֵי – beyerekah

Asshur is there and all her company: his graves are about him: all of them slain, fallen by the sword: Whose graves are set in the sides of the pit, and her company is round about her grave: all of them slain, fallen by the sword, which caused terror in the land of the living.

(Ezekiel 32:22-23) KJV

Once you enter the great gulf nothing can stop your fall into the core. The pit is everything below the mantle. If the sides of the pit is the lower mantle, then the pit includes the great gulf.

The word translated as sides is from the Hebrew root yerekah. We encountered this before when we looked at references to the ends of the earth. We considered that the phrase the ends of the earth may simply be referring to the coast, where the land meets the sea. The Bible also uses the phrase the coasts of the earth, which is an occurrence of the word yerekah. A possible translation could be the coasts of the pit.

Sides: בְּיַרְכְּתֵי – beyerekah

• flank, side, extreme parts, recesses fem. dec. 5b.
  1. thigh; the corners out of the thigh, i.e. the descendants of; hip upon thigh, i.e. wholly; to smite upon the thigh, in token of distress.
  2. of inanimate things, the shank of the candlestick in the tabernacle; side of a tent.
• Du. both thighs.
  • fem., with suff. dec. 11c, a side, as of a country, Ge. 49:13.
    1. hinder part, hinder side, of a building.
    2. hindmost, innermost parts, recesses.
    3. remotest parts, as of the earth, the north.

Davidson Analytical Hebrew and Chaldee Lexicon page CCXLVIII