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article i nfo Effects of climate change, retreating glaciers, and changing storm patterns on debris flow hazards concern managers in the Cascade Range (USA) and mountainous areas worldwide. During an intense rainstorm in November 2006, seven debris flows initiated from proglacial gullies of separate basins on the flanks of Mount Rainier. Gully heads at glacier termini and widespread failure of gully walls imply that overland flow was trans- formed into debris flow along gullies. We characterized gully change and morphology, and assessed spatial distributions of debris flows to infer the processes and conditions for debris flow initiation. Slopes at gully heads were greater than ~0.35 m m �1 (19°) and exhibited a significant negative relationship with drainage area. A break in slope-drainage area trends among debris flow gullies also occurs at ~0.35 m m �1 , representing a possible transition to fluvial sediment transport and erosion. An interpreted hybrid model of debris flow initi- ation involves bed failure near gully heads followed by sediment recruitment from gully walls along gully lengths. Estimates of sediment volume loss from gully walls demonstrate the importance of sediment inputs along gullies for increasing debris flow volumes. Basin comparisons revealed significantly steeper drainage networks and higher elevations in debris flow-producing than non-debris flow-producing proglacial areas. The high slopes and elevations of debris flow-producing proglacial areas reflect positive slope-elevation trends for the Mount Rainier volcano. Glacier extent therefore controls the slope distribution in proglacial areas, and thus potential for debris flow generation. As a result, debris flow activity may increase as glacier termini retreat onto slopes inclined at angles above debris flow initiation thresholds.

The upper reach of the Hutuo River flows along the Xin-Ding basin and cuts a transverse drainage through the Xizhou Mountain and the Taihang Range into the North China Plain. Previous studies showed that the Xin-Ding basin was occupied by a lake during the early-middle Pleistocene. However, the timing of the paleolake breach and the mechanism for the creation of the transverse drainage are unknown. We constructed the fluvial terrace sequence in the upper reach of the Hutuo drainage combined with thermoluminescence (TL) and optically stimulated luminescence (OSL) dating, as well as the timescale of the overlying loess–paleosol sequence. Our results reveal that (1) five terraces (T5–T1) developed along the upper reach of the Hutuo River, amongst which terraces T4–T1 were formed synchronously at ~ 600, ~ 120–130, ~ 20–26 and ~ 6–7 ka, respectively; (2) the creation of the transverse drainage and breach of the Xin-Ding paleolake occurred between ~ 600 and ~ 130 ka; and (3) the mechanism for the creation of the transverse drainage is via river piracy of paleostreams on both sides of the drainage divide. Localized differential uplift and associated tilting of the Xizhou Mountain block during the middle Pleistocene result in the formation of the transverse drainage and breach of the Xin-Ding paleolake.

New data indicate that northeast-directed extensional faulting characterizes slip across the Brothers fault zone (BFZ), which marks the northern limit of the northwestern Basin and Range (NWBR) extensional province in southeastern Oregon. Structural separation across individual north-northeast striking NWBR faults decreases to zero south of the BFZ. Field relationships and cross-sections demonstrate limited kinematic linkage and independent evolution of the two fault systems since ∼7 Ma. West-directed extension accumulated on NWBR faults at 0.01 mm/yr and lengthened northward after 7.05 Ma. BFZ faults accumulated northeast-directed extension at rates of 0.01 mm/yr since 5.68 Ma. Deformation coincides with periods of heightened basaltic magmatism in the High Lava Plains, implying that volcanism weakened the crust and promoted extension in the BFZ. In a new model, we reconcile the observed northward diminishing rate and clockwise motion of the modern NWBR deformation field with regional geology. The BFZ defines a small circle about the pole of rotation and separates a stable block to the NE from the extending region to the south. Faults to the south are growing northward, consistent with the northward decrease in rate and magnitude of extension in the NWBR.

Glacial retreat and opening of Taan Fjord (an arm of Icy Bay, Alaska) in the last two decades drove a base level fall of ∼ 400 m at the outlets of four tributary valleys in the region of the current Tyndall Glacier terminus. Response in the tributary valleys to this base level fall includes evacuation of stored sediment, incision of slot gorges into bedrock, and landsliding on valley walls. Fluvial transfer of eroded bedrock, glacial deposits, and stored nonglacial fluvial deposits after 1983 resulted in progradation of fan deltas toward the fjord centerline at the outlet of each of the four catchments. In the largest nonglacial tributary valley, ∼ 0.08 km 3 (∼ 8%) of the 0.59 km 3 of > 500-m-thick stored fluvial and colluvial deposits has been transferred to the adjacent fjord. A percentage of the fjord sedimentation in the last two decades thus includes material eroded from bedrock and stored in the landscape during the previous glacial expansions. Distal deltaic deposits extend across the fjord floor and likely interfinger with distal proglacial deltaic deposits sourced from the Tyndall Glacier. A paraglacial landscape response, such as the one exhibited in upper Taan Fjord where sediment delivery to fjords from tributary sources in synchrony with sediment produced by primary bedrock erosion by glaciers, helps to explain the order-of-magnitude discrepancy between sediment yields from Alaskan tidewater glaciers on 10 0 - to 10 2 -year timescales and sediment yields and exhumation rates on 10 4 - to 10 6 -year timescales.

Spatial and temporal patterns of exhumation are inextricably linked to patterns of crustal deformation because crustal deformation drives rock uplift. A new interpretation of a segment of the Pacific-North America transpressional plate boundary in southern California is analyzed in the context of crustal shortening, rock uplift, and exhumation. Deformation is partitioned between two structural anticlinoria formed above thrust faults that root into a mid-crustal decollement. The southern anticlinorium began growing after 5 Ma and is characterized by almost no topographic expression, rock uplift of ∼3 km, and exhumation of

New mapping, structural analysis and magnetostratigraphy reveal a polyphase deformational history at the leading edge of the Spanish Pyrenean foreland fold-and-thrust belt. The present structural architecture is the consequence of three discrete periods of deformation. Map relationships between four syntectonic units and major structures provide tight geometric and age constraints for each deformational period (D1: 55 to 42 Ma; D2: 30.1 to 28.0 Ma; D3: 27.9 to < 25.8 Ma). Most of the shortening in the area accumulated during D2 thrusting at rates which varied from 0.7 mm y −1 to 2.8 mm y −1 along strike from northwest to southeast, respectively. Removal of D2 and D3 displacement on thrust faults restores folds formed during D1. A sequential kinematic history during which an individual structure accommodates shortening by folding, tightening of the fold and subsequent truncation by thrust faulting is inferred. Sequential restoration of three serial cross-sections demonstrates that nearly every structure active during D1 was also active during D2. Distributed deformation characterizes the temporal and spatial pattern on all time scales, from structures active during each individual deformational period to the long-term history encompassed by the total deformation.