Should you wish to consult the literature referred to in my Aspidella poster at the ISECT 2017 conference, it is as follows:

Billings, E. 1872: On some fossils from the Primordial rocks of Newfoundland. Naturaliste Canadien, 6, p. 465-479.
Boyce & Reynolds (2008): http://bit.ly/2sV42NX
Gehling et al. (2000): http://bit.ly/2suzZ1X
Menon et al. (2013): http://bit.ly/2suORO4

Pen-y-Ghent (image from Wikimedia Commons)

The PowerPoint slides for my University of York Centre for Lifelong Learning day class on the ‘Geology of the Yorkshire Dales’ can be downloaded here:

Part 1 (Intro/Early Palaeozoic): 2016GYD_1Intro_SML

Part 2 (Early Carboniferous): 2016GYD_2LowerCarb_SML

Part 3 (Late Carboniferous): 2016GYD_3UpperCarb_SML

Part 4 (Quaternary): 2016GYD_4Glacial_SML

Useful links

Geology of the Yorkshire Dales National Park (Yorkshire Dales National Park guide)

Geology of the Yorkshire Dales (Out of Oblivion project)

The Geology of the Yorkshire Dales (brief intro)

Yorkshire Dales: Landscape & Geology (Tony Waltham book)

Carboniferous geology of the southern UK (BGS Earthwise)

Yoredale Group, Northern England (BGS Earthwise)