Why’d does the northern part of the northern part Europe plains contain many swamps and lakes

Its numerous lakes and swamps caused by the disarranged and immature drainage pattern, together with its thin soils and coniferous forests, the Finnish plain is similar in character and appearance to northern and eastern Canada, another heavily glaciated Precambrian Shield area.

Answermost of the time it would be ground into fine sediment,and sometimes they are carried away from the original location;