The coast of Ceredigion is made up of a long coastal plain that contains high cliffs, coves, large bays and estuaries. The coastal plain gets narrower towards the more mountainous north of the county and is cut by the wide estuaries of the Teifi and the Dyfi. The broad and fertile Teifi valley is ideal for dairy farming and mixed farming. Heavy rainfall washes the minerals out of the soil and results in the mountainous areas of the county having relatively poorer, acidic soils. The plough line can be as low as 700 feet, which restricts cultivation. Sea fish The sea around Ceredigion has traditionally been rich in fish and for many centuries great shoals of herring would be caught in Cardigan Bay. The fish would be landed and sold at all the Ceredigion ports, including Aberaeron, Aberporth and Aberystwyth. At Aberystwyth the volume of herring landed increased significantly after the harbour was enlarged during the eighteenth century. Here, the fish were salted between September and November and then packed in barrels for transport by train to England. Herring was also an important food source for local people and the fish were salted in the autumn for winter use. In South Wales herring are known as Ysgadenyn (or Sgadan for short); in North Wales they are known as Pennog. At Aberporth herrings were sold to the following: Sgadan Aberporth, Dau fola ac un corff, Sgadan Aberporth, Dau enaid mewn un corff Aberporth herrings, two bellies in one body. Aberporth herrings, two souls in one body Swper Scadan, or Supper Herrings, is a traditional baked dish from the area and contains six to eight herrings which have been cleaned, scaled and filleted. A seasoning of mustard, salt and ground black pepper is spread on the inside of each herring fillet and the fillets are then rolled and laid on top of layers of thin potato slices, onions and apples, which form a base. The whole dish is topped off with more sliced potatoes, additional seasoning and a dessert spoon of sage. Boiling water is added and then the dish is baked in foil which is removed, when nearly ready, in order to brown the potatoes. Historically, this dish is considered to be an interesting recipe because it reflects the simplicity of the traditional Welsh kitchen prior to the introduction of the frying pan. At this time boiling, roasting and stewing were