Image: Iravatham Mahadevan
Image: Iravatham Mahadevan

In this symbol, two roads converge, but the point where they should meet is blocked. Hence, Mahadevan's sign number 4001 is an ideograph for the noun ravine.

Illustrative Text Reference:

Mohenjo-daro: Seal: M-626 a: Sayid Ghulam Mustafa Shah and Asko Parpola, 1991: Corpus of Indus Seals and Inscriptions: Volume 2: Page 7: Collections in Pakistan: Suomalainen Tiedeakatemia.

Image Credit:

Indus Script Sign Number 4001: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.