digLayer

function dig()
  while turtle.detectUp() do
    turtle.digUp()
  end
  while turtle.detect() do
    turtle.dig()
  end
  while turtle.detectDown() do
    turtle.digDown()
  end
end

function digRow(n)
  for i = 1,n do
    dig()
    turtle.forward()
  end
end

function digBlock()
  for i = 1, 6 do
    digRow(11)
    turtle.turnRight()
    digRow(1)
    turtle.turnRight()
    digRow(11)
    turtle.turnLeft()
    digRow(1)
    turtle.turnLeft()
  end
end

function digLayer()
  digBlock()
  turtle.turnLeft()
  digRow(1)
  for x = 1,3 do
    turtle.digDown()
    turtle.down()
  end
end

for i = 1,16 do
  digLayer()
end