Is the soil in parts of the northeast is very rocky?

Yes it is. Because during the ice age, glaciers would wear down rocks, and then when the glaciers melted, all of those pebbles were left in the soil. And it is specifically in the northeast because the northeast is the only part of America that the glaciers reached.

Answer islamic scholars made advancements in technology, literature, philosophy, mathematics, astronomy, and the arts during this time period;