When you talk to Abelard, he gives you a piece of clay and you are requested to bring imprints of stone monuments from around Vana'diel. These are found in all the outdoor areas, not in dungeons. Trade the clay to the monument to get an imprint, take the imprint back to Abelard and repeat for the other monuments. There are 17 monuments in total. You will receive money for each of them depending on the difficulty, and once you have done 15, you automatically receive a map for Crawlers Nest. After you get the map, you can receive the clay again for the next monument. But since you are likely to want the Crawlers Nest map before you are a high enough level to get the last two imprints (from Battallia and Sauromugue), I recommend this strategy.