What effect did the Moon have on the Earth 900 million years ago when it was 21,250 miles closer?

Tidal forces vary as the third power of the distance between the two bodies, so I would suppose that by changing the orbit of the Moon inwards by about 10 percent, that the tides raised on the Earth would be 1.1^3 = about 33 percent higher than what they are now, overall. The effect would be to make a typical water tide way back then, look like the occasional Perigean Spring Tide we get today that causes lots of flooding problems. The action of the water tides upon coastal areas would be much more vigorous causing increased erosion. The Earth would also be spinning faster such that there would be about 410 days to the year rather than 365 as there are now.