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Rocks & Fossils

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Younger Dryas Impact layer on Santa Rosa Island

I have read about the notably dark sedimentary layer within the Beechers Bay Formation at Arlington Springs Canyon at Santa Rosa Island. According to Kennett et al., the nanodiamonds found in this layer indicate a possible impact event. Dr. Johnson has referred to this finding in a recent webinar.  Is there any place where such a layer can be seen along the coast of Santa Rosa Island between the landing pier toward Water Canyon to Black Rock Point? Or has it been seen only at Arlington Springs Canyon?

Susie, Santa Barbara - September 15, 2021

Curator Response

Hi Susie,

Thank you for asking about this interesting topic. There are black layers visible in the stream-cut banks in many canyons on Santa Rosa Island, but they don’t all date to the Younger Dryas. The creation of a dark-colored sediment can have many causes. A researcher doesn’t know unless he/she does some radiocarbon dating whether a particular black layer corresponds to the Younger Dryas Black Layer that we identified in Arlington Canyon.

Stay curious,

Curator of Anthropology John R. Johnson, Ph.D.

Susie response:

Dear Dr. Johnson, 

Thanks for your response. I will be at SRI with Sabina and others, and we may have a chance to get a little way into Water Canyon, where, according to Wooley et al. (1998 field guide), there may be some interesting exposures. If we see something we'll take pictures.