Aligned Lakes and Landforms



The PZ Ejecta category of aligned lakes includes the Carolina bays of the Southeastern US seaboard, and the aligned bays of Alaska's Point Barrow and those on the Tuktoyaktuk Peninsula in Canada's NWT.

Aligned lake structures and "splash" structures are also visible across Western Australian, Central Argentina and Eastern South Africa.

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Oriented lakes in South Africa

They application of the PZ hypothesis finds these to be simple ejecta structures. The concept is developed in the Ejecta Morphology section, and the subsection discussing Carolina bays in particular.

The geological formation described by a shallow, elliptical structure, rimmed by a low ridge is also common in Texas, al least until the farmers leveled them.

UNDRAINED DEPRESSIONS Among the most abundant local features on the Lissie and Beaumont surfaces are the many rounded to irregular undrained depressions, 50 to 250 meters in largest dimension of probably wind-deflation origin. These are best seen shown on the one-foot contour interval maps prepared before 1925. On the these maps the many of the undrained depressions are partly enclosed by raised rims less than two feet (0.65 m) in height. Similar depressions are found in a few places on flatter parts of the Willis surface. On the Lissie and Willis surfaces the depressions seem to be randomly scattered; on the Beaumont surface they are confined to the sandy and loamy soils on meander ridges. The rims probably accumulated as the result of vegetation trapping sand and aggregates of silt and clay that were blown out of the depressions during dry periods. Though the older one-foot contour interval maps show these rims by the hundreds, landleveling for and cultivation has destroyed almost all of them. These small scale features of the Lissie surface have not been extensively described in the geologic or soils literature.

One of the few references to them is in Geib and Bushnell (1928:1942) where they are described in passing in the discussion of the Edna very fine sandy loam:Drainage is imperfect and many crawfish holes have been formed. The areas are flat or billowy, similar to the areas of other prairie soils and havenumerous mounds and depressions. These depressions are from 6 inches to 2 feet below the general level of the surrounding plain....Many of these depressed areas are surrounded by low ridges of sandy material, probably of wind-blown origin, which range from 6 to 12 inches in height and from 10 to 20 feet in width.

The main rival theory for the origin of these undrained depressions on the Pleistocene surfaces on the Louisiana and Texas Gulf Coast was proposed by H. N. Fisk (1940:75-78) who suggested that the undrained depressions are the last unfilled parts of the deeper parts (thalwegs) of abandoned and avulsed point bar swales, and channel remnants of the streams that deposited the several Pleistocene formations. The point bar swales and channels were mostly filled with flood basin or overbank deposits during the terminal slackwater stages of flooding contemporaneous adjacent active streams. He referred to these depressions as "pocks" or "pock marks" in a facetious dermatological analog to "pimple" mounds. from

GEOMORPHOLOGY AND SURFACE GEOLOGY OF HARRIS COUNTY AND
ADJACENT PARTS OF BRAZORIA, FORT BEND, LIBERTY, MONTGOMERY, AND
WALLER COUNTIES, TEXAS
By Saul Aronow,

Aronow refers to the "Pimple Mound". The geological attribution for the creation and maintenance of these Texas mounds, along with the associated Mima Mounds in Washington State, are seen by us as being highly associated with this topic of Aligned Lakes. A discussion of the standing mounds is offered in the Geological Enigmas section.