New York was heavily glaciated in the ice age leaving much of the state with deep, fertile, though somewhat rocky soils. Row crops, including hay, corn, wheat, oats, barley, and soybeans, are grown. Particularly in the western part of the state, sweet corn, peas, carrots, squash, cucumbers and other vegetables are grown. The Hudson and Mohawk Valleys are known for pumpkins and blueberries. The glaciers also left numerous swampy areas, which have been drained for the rich humus soils called muckland which is mostly used for onions, potatoes, celery and other vegetables. Dairy farms are present throughout much of the state. Cheese is a major product, often produced by Amish or Mennonite farm cheeseries. New York is rich in nectar-producing plants and is a major honey-producing state. The honeybees are also used for pollination of fruits and vegetables. Most commercial beekeepers are migratory, taking their hives to southern states for the winter. Most cities have Farmers' markets which are well supplied by local farmers.