The River Thames runs straight through the City of London. People have lived beside it for thousands of years. Like the sea, the river is tidal(有潮的). When the tide goes out, the muddy foreshore(泥泞的滩地) can be seen: For as long as people have been living beside this river, they have been throwing things into it such as rubbish, or maybe something valuable. The River Thames holds many secrets.
During the 18th century, many poor people would stand in the river's mud when the tide was out. They would search for hidden treasures. They did not expect to find anything of real value like coins or jewels (珠宝), but simple objects they could sell or trade for food. They were known as mud larks. The job was never easy, because the water could be freezing cold.
Today, people continue to search the foreshore for hidden treasures. It's different from over 200 years ago. All mud larks in the River Thames now need to have a license. Anything they find of historic interest has to be reported to the Museum of London.
Recently, Londoner Martin Bushel was mud larking. He found something that looked like the top of a human skull (头盖骨). He called the police and passed it onto them. When he was walking by the river a few days later, he saw some policemen searching the area. He was worried that he might become involved in a murder case(卷入一起谋杀案). Later he received a phone call telling him that what he had found was really from a human skull. However, it was5, 600 years old and was put on show in the Museum of London.
