150 year Comparison of Giant and Castle Geysers, Yellowstone

Comparison of photos from Giant and Castle Geysers separated by almost 150 years. These images suggest almost no changes to the geyser structure implying that large geysers form over thousands of years. 

Photo credits: Top left: U.S. Geological Survey Denver Library Photographic Collection, Jackson, W.H. Collection. Top right: NPS public domain.  Lower left: U.S. Geological Survey Denver Library Photographic Collection, Jackson, W.H. Bound Album Collection, (200)1 HMi 1871 v. 2. Lower right: NPS / Jacob W. Frank