1) Became more intense 2) Concentrated 3) Dug further 4) Dug more 5) Dug out a bit more 6) Excavated further 7) Gathered 8) Gave more capacity to 9) Got lower 10) Got more complicated 11) Increased in depth 12) Intensified 13) Used a dredge 1) Concentrated 2) Gathered 3) Grew 
• (imp. & p. p.) of Deepen