Guanylate cyclase and the adrenal natriuretic factor receptor.

river valleys, across the Alpine fault, and deposited estuarine silts with marine bivalves in the 250-km-long region between Haast and Kaniere (8). Former islands and peninsulas northwest of the fault were notched by sea-level highstands; close terrace spacings indicate much slower uplift than for the Southem Alps. We believe the available data show that the accordant steps are marine terrace time lines that can be used for inferring uplift and erosion rates. Alternative hypotheses for the origin of accordant bedrock benches with rounded quartz pebbles fail simple tests. It is apparent that moas did not violently thrash rocks in the gizzards and later deposit them selectively on flat topographic steps. Neither glaciers nor streams can account for (i) flat shore-parallel benches more than 5 km long or (ii) the presence of rounded quartz pebbles on flat summits along the main divide of the Southern Alps. Gradual spatial changes in lithospheric properties and stress fields are reflected by changes in uplift rates along the Alpine fault. The temporal doubling of inferred uplift rates at about 135 x 103 years ago may be the result of a structural realignment brought about by progressively larger convergence between the Pacific and Australian plates. WiLLum B. BULL Department fGeoscences, Univerity ofArizona, Tucson, AZ 85721 A. F. COOPER Department ofGeology, University ofOtago, Dunedin, New Zealand