I'll take the last error first. The St. Peter Sandstone contains three units, the Readstown, Tonti, and Glenwood Members. Each of these has a mix of wind deposited, and marine strata, or layers. We recognize wind born sand by the sediment structure or pattern, and the very well sorted grain size. Taking the middle of the St. Peter Formation's three sub-units, it has a large scale structure of hundreds of square kilometers of cross-bedded wind dunes, with occasional marine beds with micro-bedding, burrows, and shelly species similar to shallow water habitat today. Where we find this exact pattern today is in the Namibian Desert. Sand dunes hundreds of feet high stretch for thousands of square kilometers, and the ocean periodically intrudes, creating shallow sandy coves, and bays. These can persist for years, becoming colonized by invertebrates until they buried by the returning dunes. The sand that was washed out by the waves and tides is re-deposited by the near shore currents. This also rounds, and polishes the individual sand grains.
This latter fact also destroyed Olson's assertion that the St. Peter Formation's well sorted, rounded sands were part of a high energy "rapid current" forming river deltas. In fact, river sands have a rough texture and under a microscope, individual grains have many sharp angles, and projections and they also vary considerably in size. When studied microscopically, the St. Peter Formation Sandstone is well rounded, and remarkably uniform in grain size. The geochemical analysis of the St. Peter Sandstone also reveals the interesting fact that the silicate binder, or "cement" weakly connecting individual grains was genearted by plain rain water, well after the shallow ocean had retreated from central North America.
The St. Peter Sandstone in fact varies in depth from less than a meter, to just over 120 meters. The uppermost surface of the St. Peter Formation is particularly flat. What is a strong confirmation of an ancient Earth is that the depth variation is mostly due to irregularity in the bottom of the deposits. These Ordovician Era sands rest on top of the ~570-505 million year old Cambrian deposits. The ancient Cambrian surface had been exposed to air, and eroded with deep canyons over tens of thousands of years, if not even longer. What Ross Olson has not apparently considered at all is that the St. Peter Formation is capped with additional millions of years of sediments in places over a mile thick, although mostly the regional overburden thickness has been less than half that.
Below are some freely available references to competent studies of the St. Peter Sandstone Formation;
Twin Cities Geology
Mai H. and Dott, Jr., R. H. (1985) "A subsurface study of the St. Peter Sandstone in southern and eastern Wisconsin" Wisc. Geol. Nat. Hist. Surv. Info. Circ. 47, p. 26.
Jacque L. Kelly, Bin Fu, Noriko T. Kita, John W. Valley 2007 "Optically continuous silcrete quartz cements of the St. Peter Sandstone: High precision oxygen isotope analysis by ion microprobe" Geochimica et Cosmochimica Acta 71:3812–3832