Article: Middle Old Red Sandstone spore assemblages from the Orcadian basin, north-east Scotland

Spore assemblages have been found in a variety of Middle Old Red Sandstone deposits sampled from several areas in the Orcadian basin, ranging from the south side of the Moray Firth in the south to the Orkney Islands in the north. New taxa include Subturma Pseudosaccititriletes and four genera, Acinosporites, Corystisporites, Dibolisporites, and Samarisporites; eighteen species and two varieties are new, and in addition the genus Retusotriletes (Naumova) is emended and restricted to laevigate spores in which well-developed curvaturae perfectae are a constant character; many of the other species described are new combinations of Eisenack (1944), or of various species of Russian authors.The vertical distribution of spore assemblages in the Orcadian area is described and several points of local correlation discussed. Detailed comparisons with Russian spore assemblages are made and a correlation between the north-west Russian and Orcadian sequences is suggested. Characteristic features of Devonian, especially Middle Devonian spore assemblages are discussed. Apart from the spores no other acid-resistant microfossils have been found except for fragments of plant and fish tissues; the possible significance of this is discussed below.