Given the task definition and input, reply with output. In this task, you're given a pair of sentences, sentence 1 and sentence 2. Your job is to determine if the two sentences clearly agree/disagree with each other, or if this can't be determined. Indicate your answer as yes or no respectively.

Sentence 1: By this time, the valley was in much the same geographic state as it exists in today, with one exception the presence of artesian springs that bubbled to the surface in several areas. Sentence 2: Artesian springs have changed over time.
yes