Valmiki Ramayana Yuddha Kanda Sarga 42 Shloka 16

वानराः Vanaras, पारिखाः with soil, पर्वताग्रैश्च with mountain peaks, तृणैः with grass, काष्ठैश्च wooden pieces, पांसुभिः moats also, प्रसन्नसलिलायुताः with pure water, पूरयन्ति filled.

The Vanaras started filling the moats with soil, pure water, logs of wood, grass, and mountain peaks.