The storage and persistence of soil organic matter (SOM) is of critical importance to soil health, and to the terrestrial carbon cycle with implications for long-term climate change. To better understand the spatio-temporal controls on SOM, we have developed a new dataset spanning two previously described marine terrace soil chronosequences from northern, CA, USA: the Santa Cruz and the Mattole River chronosequences. Each of these sites, is comprised of several terraces surfaces that span at least 200 ka of soil development. The sites differ with regard to local precipitation, with the Mattole site receiving nearly double the mean annual precipitation of the Santa Cruz site. During the period from 2011 through 2016, we collected and analyzed samples from eight soil pits (four at each chronosequence site) in order to facilitate the comparison of SOM content and isotopic composition with other soil biogeochemical measurements. In the resulting climo-chronosequence dataset, we report depth resolved carbon and nitrogen concentration and carbon isotopes (13C and 14C) along with measurements of soil texture, surface area, mineralogy, pH, and elemental chemistry.