From Bulbapedia, the community-driven Pokémon encyclopedia.
Professor Alden (Japanese: ウメズ教授 Professor Umezu) was a one-time character of the anime who appeared in the episode A Ruin with a View. He is an archaeologist who had his base in the Pokémon Center of Oldale Town as he studied the Oldale Ruins.
He showed Ash and May the nearby Oldale Ruins and informed them about the Pokémon that resided there. Suddenly Team Magma members arrived and blackmailed Alden so that he could give them access to the ruins. He was then kidnapped by Team Magma. Ultimately, he succumbed to their threats and opened up a secret chamber of the ruins with the help of four colored orbs for the Magma members to enter. Team Magma inspected the room and then went away dissatisfied, leaving Alden unharmed.
Ash and May arrived on the scene just too late and saw Team Magma escaping in a helicopter. The Professor then took them to a deeper part of the ruins after Pikachu Thunderbolted Team Rocket away. There, he showed them a lake filled with the prehistoric Pokémon Relicanth.