The New York State bedrock contained salt, gypsum and hematite during the Silurian age. The Silurian age started around 443.8 million years ago. The bedrock gives scientists a clear indication of when each age started and ended. The Silurian age is also an important period in the evolution of life on the earth. During this age, life began to appear on the land in the form of small, moss-like, vascular plants. They started growing next to lakes, coastlines and streams. Small terrestrial arthropods also starting appearing during the Silurian age.