Trench

With scooping gestures, you cause the ground to slowly sink into a trench 5 feet deep, 5 feet across, and 60 feet long. The trench forms slowly enough that enemies have no chance of falling into it. 

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the trench's width increases by 5 feet or the length by 30 feet for each slot level above 2nd. You can make a different choice (width or length) for each slot level above 2nd.