Recorded in many forms as shown below, this interesting name is Medieval English. It is locational from a "lost" village, which is named from the pre 7th Century words "caerse" meaning water cress, and "lacu", a lake, thus a stream where water-cress grew. The phenomenon of the lost village was a result of enforced land clearance in the 12th and 13th centuries, at the height of the wool industry, to make way for sheep pasture. It is estimated that five thousand such places have disappeared from British maps, and most have given rise to surname. When people left their birthplace to seek work elsewhere they would often adopt or be given as their surname, the name of their former village as an easy means of identification, thus resulting in a wide dispersal of the name. The modern surname can be found as Carslake, Caslake, Carslaw, and others. The first recorded spelling of the family name is shown to be that of Ranulph de Carselak. This was dated 1279, in the Assize Rolls of Somerset, during the reign of King Edward 1st, known as "The Hammer of the Scots", 1272 - 1307. Surnames became necessary when governments introduced personal taxation. In England this was sometimes known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.