proceedings: geological society 411 



area of about 10 square miles. This portion slopes to the southwest 

 from the foot of the Valdez Glacier at an elevation of 250 feet to tide- 

 water, a distance of 4 miles. At the foot of the glacier the delta is IJ 

 miles across. The lower edge is 4 miles in length. The submarine 

 frontal slope of the delta is steep, ranging from 6^ to 21 degrees. It 

 joins the subaerial portion of the delta at a sharp angle, and before the 

 construction of the present wharves large ocean vessels could at low 

 tide moor in deep water along the delta front and safely discharge their 

 cargo by derrick onto dry land. The junction of this frontal slope with 

 the gently sloping fiord floor is much less abrupt but in some places seems 

 to be quite sharp. The thickness of the delta gravels may be estimated 

 by constructing cross sections of the delta. The delta materials rest 

 on a basement of metamorphic rocks. Intense glacial erosion has 

 impressed on this bedrock a characteristic topography markedly differ- 

 ent from the constructional topography of the delta. By a comparison 

 of the delta profiles crossing the junction of these two types of topog- 

 raphy it is possible to locate approximately the base of the delta gravels 

 and to determine the thickness of the delta deposits as probably a little 

 over 300 feet. 



R. S. Bassler: Paleozoic rocks and fossils on the Piedmont of Mary- 

 land. The western part of the Piedmont plateau in Maryland and 

 Virginia contains areas of early Paleozoic limestone infolded in the 

 pre-Cambrian crystallines and overlain in part by the Triassic (Newark) 

 series. These limestones outcrop at one point next to the early Cam- 

 brian Harpers shale, and hitherto it has been believed that they rep- 

 resented the Shenandoah limestones of the Appalachian Valley, 

 comprising strata from early Cambrian to Middle Ordovician time. 

 Detailed mapping of this area and the discovery of fossils have shown that 

 this Piedmont limestone consists of a lower massive limestone division 

 containing Lower Beekmantown fossils and an upper thin-bedded 

 dark blue limestone with a Chazyan fauna, the two separated by a well- 

 marked disconformity. The Lower Beekmantown division can be cor- 

 related directly with strata in the Appalachian Valley but the Chazj'an 

 portion has no representative there. 



O. E, Meinzer: The glacial history of Columbia River in the Big Bend 

 region. In the Glacial epoch a lobe of the ice sheet was pushed down 

 the valley of Okanogan River, in north-central Washington, and across 

 Columbia River, diverting the waters of the Columbia over the upland 

 of central Washington. In its new course the river cut precipitous 

 gorges several hundred feet deep, developed three cataracts, at least one 

 of which was larger than Niagara, formed a large lake in Quincy Valley, 

 and performed an almost incredible amount of work in carrying boul- 

 ders many miles and gouging out holes as much as 200 feet deep. The 

 upper part of this abandoned channel of the Columbia has been described 

 by T. W. Sj^mons, I. C. Russell, and F. C. Calkins. Both Symons and 

 Russell made vague references to a very large Pleistocene Lake, which 

 Symons called Lake Lewis. In the fall of 1916, A. T. Schwennesen 

 made an investigation of the water resources of Quincy Valley (see 



