Simplify the following text for a Grade 10 native English-speaking person.
Original: Shyok river ( a tributary of the Indus ) originates from the Rimo glacier , one of the tongues of Siachen Glacier and becomes very wide at the confluence with the Nubra River ( a tributary of Shyok , originating from Siachen Glacier ) .
Simplified: The Shyok River , a tributary of the Indus River , originates from the Rimo Glacier , one of the tongues of Siachen Glacier .