Northwest England has been affected by the Caledonian, Variscan and Alpine orogenies no one of which is entirely unrelated to the others. Each successive phase is partially dependent on earlierones, whilst structures in older rocks became modified by succeeding events. There is thus an evolutionary structural sequence, probably originating in a preCambrian basement and extending to the present. The Caledonian episodes are subdivided into pre-Borrowdale Volcanic, pre-Caradoc and end-Silurian phases. The recent suggestions of a severe pre-Borrowdale volcanic orogeny are rejected but there is a recognizable angular unconformity at the base of the volcanic rocks. The ‘pre-Borrowdales’; trends and those of the pre-Caradoc movements are variable but are generally northerly and could be posthumous upon a pre,Cambrian basement. The end-Silurian structures include early n – s and later ne to ene folding. The Variscan structures are in part determined by locations of the older massifs and in part they are likely to be posthumous upon older structures with important n – s and ne . elements. Caledonian wrench faults were reactivated, largely with dip slip movement. The more gentle Alpine structures also follow the older trends with a n – s axis of warp or tilt and substantial block faulting. The latter was a reactivation of older fault lines and resulted in uplift of the old north Pennine massifs relative to the downwarped Irish Sea Basin and the Vale of Eden.

Late Spring 1967 REPORTS 503 the physiological changes accompanying the initiation of growth are in order now that the external conditions controlling dormancy in four of the species are known. AcKNOWLEDGMENTThe authors wish to thank Dr. Orie Loucks, University of Wisconsin, for his continued interest and helpful suggestions. LITERATURE CITED Curtis, ]. T. 1959. The vegetation of Wisconsin, an ordination of plant communities. University of Wisconsin Press, Madison, Wise. 657 p. Gumpf, R. E. 1962. Some effects of soil temperatures on the dormancy break and growth responses of Erythronium albidum. M.S. Thesis. University of Wisconsin, Madison, Wise. 64 p. Kieckhefer, B. ]. 1963. Phenology and energy relations of Dicentra canadensis and D. cucullaria.Abstract. Tlzalassia tcstudillltlll Konig and Sims and Halophila enyclmanni Aschers. (Hydrocharitaceae) ; Dip!anthera wrightii (Aschers.) Aschers., Ruppia maritima L., and Syrinyodium fi!iforme Kutzing ( Potamogetonaceae) are the major plants of the highly productive estuaries along the Texas coast. When transplanted to outdoor ponds and to controlled growth rooms, the greatest tolerance to increasing salinity was shown by Diplmztltera. Lesser salinity tolerance was shown by Thalassia and Ruppia. Although survival was not complete under all transplant conditions for Syringodium, it showed least tolerance of high salinity. Ha/op/zi!a survived sporadically in the study but showed active growth at high salinity. The distributional p:~tterns of these species in Redfish Bay are partially correlated with their salinity tolerances.

The Masirah Ophiolite consists of serpentinites, gabbroic intrusions, an extensive sheeted dyke complex, pillow lavas, and sediments. It is truncated to the W by a NNE-trending, 5 km wide vertical mélange zone: a megabreccia with blocks up to 2 km long of all the above lithologies. The mélange trend is perpendicular to that of the sheeted dyke complex, a common relationship between a transform fault and spreading centre. Many of the features of the mélange can be explained by serpentinite diapirism along a major ocean crust fracture. However, the distribution of other reported ophiolites along the SE coast of Arabia and the intrusion of the Masirah Ophiolite by granite, whose geochemistry indicates melting of continental crust, both suggest upthrust of ocean crust onto the Arabian continent. The Masirah Mélange and the dyke trends within the ophiolite are parallel, respectively, to the Owen Fracture (and other transforms) and to magnetic anomalies in the Indian Ocean. It is suggested that both mélange and ophiolite are related to a late Cretaceous stage in the evolution of the Indian Ocean, and may not correlate with the Semail Ophiolite of the Oman Mountains, as has been previously supposed.

Acritarchs of Lower Cambrian age have been recovered from a clay horizon within conglomerates 6 m above the unconformity described by Cope & Gibbons (1987). The Wrekin Quartzite (34 m thick) represents beach deposits grading upwards into shelf sandstones. The stratigraphic evidence and recent age determinations suggest that although the granophyre was intruded at 560 ± 1 Ma the Cambrian Unconformity is younger than 533 ± 13 Ma.

Summary The Carboniferous succession exposed along the Sykes Anticline includes the upper part of the Viséan Series and the lower part of the Namurian Series. The Viséan succession consists of the upper 350 feet of the Worston Group and the Lower Bowland Shales. The Namurian strata of lower Pendleian (E 1 ) age include the Upper Bowland Shales and the Pendle Grit. The sequence is conformable and very similar to that described by Parkinson (1936) in the adjacent Slaidburn district. The anticline is a concentric fold with relatively competent upper and lower levels separated by an incompetent sandwich of shales. The upper level (Pendle Grit) has the general form of a boxfold with dips of about thirty-five degrees on the limbs, an axial zone about a mile wide and a trend of 045 degrees. The lower level (Worston Group) is tightly folded into en echelon periclines with vertical and overturned strata common, and a mean axial trend of 027 degrees. The difference in tectonic style between upper and lower structural levels is attributed partly to the normal process of concentric folding, with the crumpled limestones indicating a lower limit to this, and partly to the disharmony of the Bowland Shales. Dip, strike and oblique joints are found in several well-defined sets, each set related to the anticlinal structure and approximately normal to the bedding.