First drop 40 dirt on each corner of the 2x2 area.
Note that once the slope gets over 20 dirt, to get up/down from this 2x2 area will not be easy because you may need to climb.
Advice is to make a pile for the dirt (using any object on you, its easier with different items as this will form a "pile of items", which is easier to target) on the slope and then add the dirt (from your cart), and retrieve your items, repeat until your pile(s) have 100 dirt so you don't have to keep climbing up/down.
Once the outer slopes are 40 dirt, start dropping dirt (batches of 10-20 dirt is good) in the center of the 2x2 and flatten one of the tiles (rotating the tile to flatten is a good idea, if not you had better flatten all the 4 tiles). Remember not to stand on the high point when flattening as you will get "Ouches".
===Notes:===
Another Option is to dig at the base of a slope to increase it, but this is not always possible (e.g. on landbridges or when doing a road along rock).
===Tips:===
Note that once the slope gets over 20 dirt, to get up/down from this 2x2 area will not be easy because you may need to climb.
Advice is to make a pile for the dirt (using any object on you, its easier with different items as this will form a "pile of items", which is easier to target) on the slope and then add the dirt (from your cart), and retrieve your items, repeat until your pile(s) have 100 dirt so you don't have to keep climbing up/down.
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